How Light Affects Our Sleep

Blue Light ComputerMost people are at least cursorily familiar with the concept of the circadian rhythm. For those who aren’t, the circadian rhythm refers to our internal, approximately 24-hour cycle of biochemical, physiological, and behavioral processes. Every living thing, from fungus to bacteria to plant to animal, has a circadian rhythm. External cues called zeitgebers (what a great word, huh?) help synchronize or alter our rhythms; they include temperature, nutrition, meal timing, social interactions pharmacological interventions (medicines, drugs), and, most prominently, the light/dark cycle of the earth.

Yes, light, or the lack thereof, plays an enormous role in the regulation of our cycles, especially our sleep cycle. For millions of years, light was an objective, exogenous measure by which organisms established behavioral patterns, hormonal fluctuations, and sleep cycles. Depending on the seasons, the position of the global axes, and the weather, you could pretty much count on light, bright days and deep, dark nights. Nocturnal hunters and scavengers took the lack of light to mean “eatin’ time,” while other animals (including humans) sought shelter and slumber when night fell. Daylight meant activity and safety (since we could, you know, see everything). Fire, then, wasn’t just about cooking and providing warmth; it also allowed humans a small sliver of daylight’s safety and security at night.

Before I go on, I need to make something clear. My regular readers will have already grasped this concept, but I think it’s a good idea to reiterate it. Though it’s tempting to place us humans on another plane of existence, apart from the mindless flora and fauna that share this world, we are animals. Sure, we’re smarter and more complex than the others, but we’re still subject to these exogenous zeitgebers worming their influential fingers into our subconscious and fiddling with our circadian rhythms. Our tendency to get sleepy when night falls isn’t a cultural relic; we didn’t consciously decide to start sleeping at night because it was too dangerous to be out in the dark. The culture of standard bedtimes arose organically, if you can even call it culture. Does the chirping of birds in the morning reflect cultural tendencies? Is “the early bird gets the worm” a standard axiom in avian academia? No – the early bird’s evolutionary niche decrees that it wake up bright and early in order to get food. It’s basic natural selection, and humans are the same way. We don’t decide to get up early. We get up early because of a complex pattern of environmental cues telling us to get up. Throughout our evolutionary development, handling business during the daytime was simply how we survived. We can’t escape nature.

But boy do we try.

The zeitgeber (can’t get enough of that word) with the biggest impact on our sleep cycle is light. Period. And it’s not just natural light that affects our sleep cycle, but also unnatural, manmade lights. That’s kinda how we operate, actually, as instinctual beings who often misinterpret “unnatural” because, well, our physiology isn’t exactly intelligent. It’s not sentient. It’s purely reactive. Blue light from a 10:00 AM sky, blue light from your computer screen at midnight – it makes no difference to our circadian rhythms. It’s all the same to our bodies, because for millions of years blue light meant daylight, not a late night blog comment section or reruns of The Daily Show. And it’s the blue light specifically that appears to monitor our sleep patterns the most.

Like insulin and inflammation, blue light is integral to our health – in the correct amounts. When we’re exposed to levels of anything in excess (or too little) of what we would have experienced for the bulk of our evolutionary history, problems arise. Blue light regulates our secretion of melatonin, the sleep hormone. Exposed to blue light, we limit the production of melatonin, and we stay alert and awake; in the absence of blue light, melatonin production ramps up, and we get sleepy. This system worked quite well for a long time. Reddish light from fire (our formerly primary source of nighttime illumination) has little to no effect on melatonin production, so sleep wasn’t disrupted when we relied on fire. These days, though, we’re subject to a steady barrage of blue light. During the day, blue light (natural or unnatural) isn’t much of a problem because we’re supposed to be awake, but at night, when we’re “supposed” to be getting ready to sleep, we tend to sit in front of blue light-emanating appliances, and our sleep suffers for it.

(An interesting note on how we respond to blue light. For years, scientists assumed circadian rhythm was set by sight (of light) alone. Person sees sky/LCD screen and the same visual system that allows colored vision determines the hormonal, behavioral, or other physical reactions to the light. It makes sense, but that’s not how it works. It turns out that there exists a second, more dominant system responsible for setting circadian rhythm based on light input. If a person’s sleep cycle depended purely on traditional color vision, we’d expect the blind to universally suffer from disrupted sleep. They do not, however, and this is explained by optical cells that express a photopigment called melanopsin. Unlike the standard rod and cone opsins, melanopsin doesn’t help us see. Instead, it reacts most strongly to blue light, and scientists think it’s the primary regulator of the biological clock and production of melatonin. In otherwise blind patients with intact melanopsin systems, blue light has a strong effect on their sleep cycles.)

Blue light has its place, of course. A British study found that blue light-enhanced white lights in the workplace improved alertness, performance, and even nighttime sleep quality in employees. That’s during the day, though, when blue light exposure is normal and expected. Nighttime exposure to blue light disrupts our sleep hormones. Television, computer screens, even digital clocks with blue numbers – they’re all common sources of late night blue light that can affect our production of melatonin.

Is blue light the only issue? It certainly appears to be the primary driver of circadian rhythm, but it’s not the only one. In a recent study, researchers found that while monochromatic blue light suppressed melatonin production via melanopsin stimulation, polychromatic white light (which includes blue light) stimulated melanopsin equally while suppressing melatonin to an even greater degree. Clearly, it’s not just blue light’s effect on melanopsin affecting our sleep cycles.

Still, blue light is the low-hanging fruit, and there are some simple steps you can take to mitigate its late-night effect on your sleep.

  • Keep electronics usage to a minimum or completely eliminate blue light (alarms, TVs, laptops) after dark.
  • Go to sleep earlier.
  • Use candlelight (read how a fellow MDA reader gave this a try for 30-days).
  • Keep your room as dark as possible and your sleeping quarters pitch black.
  • Install F.lux (totally free) on your computer to cut down on blue light emissions.
  • If you want to try a somewhat extreme experiment you could even wear orange safety glasses at night.

(Thanks to this thread on PaleoHacks for the last two tips.) Also, don’t forget to expose yourself to blue light during the day so that your cycle normalizes – it goes both ways, you know.

Does anyone have experience cutting out blue light exposure to great effect? Let the world know in the comments.

About the Author

Mark Sisson is the founder of Mark’s Daily Apple, godfather to the Primal food and lifestyle movement, and the New York Times bestselling author of The Keto Reset Diet. His latest book is Keto for Life, where he discusses how he combines the keto diet with a Primal lifestyle for optimal health and longevity. Mark is the author of numerous other books as well, including The Primal Blueprint, which was credited with turbocharging the growth of the primal/paleo movement back in 2009. After spending three decades researching and educating folks on why food is the key component to achieving and maintaining optimal wellness, Mark launched Primal Kitchen, a real-food company that creates Primal/paleo, keto, and Whole30-friendly kitchen staples.

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197 thoughts on “How Light Affects Our Sleep”

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    1. Just be safe… candles and unattended cooking are the top two causes of house fires.

      1. Yes, good advice. My concern is not an unattended candle so much as it is our cat walking by it and catches its tail on fire, jumps off the counter and dashes into the curtains.

        But I do love the candle idea, and my wife has a huge collection of them. Now that I’m ready to experiment with candle light at night, we’ll have an amalgamation of senses that include vanilla, cinnamon, wild berry, velvet, lavender, and midnight jasmine.

        Can an aroma ambush stimulate the sympathetic nervous system?

        1. re: cat’s tail knocking it off and/or curtains – that’s why I’ve started buying/acquiring on-the-wall candle holders that hold the candle INSIDE it, in a glass jar.

          Also, I only use beeswax candles. I love the smell, and it’s NOT petroleum.

    2. I love the candlelight idea. And even if it is artificial light…. if you use only a few candles then the amount of light that is produced is significantly lower then the amount of light that is produced with several lightbulbs and a glaring TV, computer, or whatever.

      When the sun goes down, our body naturally begins to go into sleep mode. It may take a couple of hours, but when its pitch black its sleep time!

      1. Candle light does not allow a person to do anything. Wash the dishes? Read? Take a shower? Please.

        I used to use kerosene lamps back in the 60s, but probably they emit poison gases. And if you turn them up high enough to read, they smoke up the chimney. And the room. And the smoke keeps the light from coming through. But it is a warm (not blue) light.

        Even so, unless we are to retire when it gets dark, we will be using electric lights. In northern areas, it gets dark in winter at 5 pm.

        I wonder about the melatonin-sleep-blue light matter for people who live in the far north where it can be light for 24 hours. Anyone?

        1. “unless we are to retire when it gets dark, electric lights”
          Electric yes. But we can more wisely choose which ones. Don’t buy the 6500K bulbs for night time use.
          I’ve got a lamp with two independent sockets/switches. A regular bulb in one and a 60watt equivalent florescent yellow “bug” light in the other so I can choose which to light depending on the time. The bug light is more than enough to read or do anything by. My 2 year old daughter cried wanting to go to bed the first night we tried it and has stopped fighting to stay up later. Last night we had a birthday party and used the normal lights and she didn’t sleep well and woke up at midnight and was up for a good while.

        2. Wash the dishes? Check. If you’re meticulous, you could do it with your eyes closed.

          Read? CHECK. People used to read under candlelight all the time. It’s totally sufficient.

          Take a shower? Check. I always shower with the lights out, actually. I can’t imagine why you’d think it would be a problem.

        3. I frequently bathe with 2 dinner candles lit, and can easily read by those whilst taking a long bubbly soak. This began by being annoyed by the automatic vent system in my bathroom that turned on with the light, it was too annoying to read with that on.

          I imagine if one is careful one could easily wash dishes by candlelight; I always put sharp knives off to the left in the sink, so that even under suds I know where they are, move the hands slowly that’s all!

          I mean, how do completely blind people wash their dishes? Carefully! (please don’t say they let the guide dog lick the plate & then put it back lol!)

    3. I sleep with a black lite on my 1960 posters in my bedroom . I sleep like a log.

  1. “zeitgeber” time giver… if my german is correct. They come up with some marvelous compound words.

    1. Yes, literally it’s “time giver” but it means “timer” 🙂 Makes sense!

  2. Very interesting! I will be interested to hear all of the comments on this.

    When I read “Lights Out” several years ago, I wondered about fire at night, moonlight, bright stars etc., and why they wouldn’t have disrupted melatonin in Grok’s time. Maybe the blue light theory explains this??

    Also, “Lights Out” mentioned that just a small amount of light from a fiberoptic scope shined on the back of a knee was enough to cause problems, so apparently it isn’t just receptors in the eyes that matter.

    Lastly, I am wondering how latitude affects melatonin comparing someone on the equator to an Alaska native? Do people just adapt to their environment or is a genetic component more important here?

  3. With the insanity of Facebook status updates (for all the self-important people) and twitter being logged in every few nanoseconds, staying away from an electronic device seems impossible for the tech-crazy Gen-X. Just go to any mall in America and looks at the teens, muffin tops busy on their cell phones. No to mention teenage boys castrating themselves with radiation from cell phones and frying their testicles with video games and not making any testosterone. Pretty soon, they would all be sitting and wathcing Oprah eating tofu burgers (or maybe they are).

    1. re: electronic devices, cell phones, etc.: You nailed it! Even though there is ample evidence that prolonged up-close cell phone use can create tumors, half the population seems to have a cell phone stuck to the side of the head (with crazy glue?). “Darwin Award” candidates abound, so hopefully the situation will prove to be self-regulating. (Says he, typing this message on his laptop… 😉 )

      1. There is no ample proof that cell phones cause tumours or any type of cancer.

        If this was the case wouldn’t we see the rate of tumours increase.

        It’s common knowledge that heat will reduce sperm production, however if you wear briefs you are just as likely to reduce your sperm count….

  4. I have bipolar disorder and it used to really wreak havoc with my sleep cycle, until I started wearing copper safety glasses after 6pm and a sleep mask at night.

    The glasses were a huge pain to get used to (and the sleep mask took time too), but it made a big difference. During the winter, I also use a lightbox for about 20 to 30 minutes every morning. This has pretty much completely normalized my sleeping routine and my energy levels. Incidentally, other bipolar symptoms are also much easier to manage and I seem to be in “remission” (symptom free) much of the time.

    It’s worth a shot for people having sleep issues.

      1. I think this is a rather sharp response. I will go and read your link, but I would say this. My grandmother was treated for, what was known then as ‘manic depression’ through her early adulthood onwards, this included EST, not something I would wish on anyone. She died age 56 from complications of uncontrolled diabetes. I was insulin resistant during two pregnancies so although not considered diabetic non gestationally clearly have a predisposition to metabolic sensitivity.

        The fact that I have hugely benefited from insulin control through Primal eating and have, for many years worked with swings that are outwith what is considered ‘normal’ that are now normalising I don’t think it unreasonable to consider there may be a link. I have only recently been open about this. Unless you have lived through (or alongside someone) in a manic epsiode I don’t think it is fair to say it’s buying into a label.

        1. I’ve just followed your link – I do not take any form of drug, I have never followed the CW on this, in fact following the history of my Grandmother’s treatment from CW (which was effectively to foreshorten her life) my family ensured I was never seen by the ‘establishment’. I have worked with an altenative thrapist at a cognitive level, not with any form of drug and have ‘learned’ my way through it. Keeping insulin low on Primal has been THE most effective ‘treatment’.

        2. I am a rehab counselor for folks with dual diagnosis–meaning they have substance abuse issues and a “mental illness.” First, I want to say that I respect you and your family’s decision to forego any pharmacological interventions. I think it would be tempting to follow the CW and its promises of miracle cures.

          While I do believe that mental illness does occur, I wish I had the freedom to experiment with nutritional and lifestyle treatments. It sounds like you have experienced some good success by changing your habits!

          I personally have complaints about the convergence of the psychiatric and psychological fields. Psychiatry attempts to frame mental illness as a medical disorder, and as such approaches conditions from a very cut-and-dry, dualistic framework. I think that approach is what Lynda refers to (though I am inclined to agree that the comment is unneccesarily cutting). But, in my observation, you have a very valid point that there is definitely something going on with mania/depression/etc.

          I wish you the best in your continued recovery, and I sincerely hope that some day we can get real, valid science which questions the efficacy of medications, nutritional intake, lifestyle choices, etc.

        3. Mickey (I hope this posts appears below yours)

          Thank you very much for your comment. It takes a great deal of bravery for many like Username above to speak more openly about this and it’s great to read a sympathetic post.

          I too passionately hope that further, proper, investigation of the effect of nutrition on a whole myriad of modern ‘conditions’ begins to pick up speed, from what I see around me the long term healthy survival of our species may well depend upon it.

          Since beginning this journey after a chance encounter with a guy on a ferry back from Spain (I kid you not) last November who impressed upon me the necessity of reading Gary Taubes Diet Delusion I’ve become increasingly convinced that a whole host of problems can be avoided – I think now about how many schools, clean water wells etc the money released from treating these illnesses would be released if the powers that be started to take note of what communities like this are discovering for themselves and trying hard to get CW to acknowledge.

          On with the crusade!

        4. Don’t you love it when people who don’t have the problem ridicule you for having it? Don’t let Lynda’s smug criticism get to you. The internet is, unfortunately, a haven for the self-anointed. In fact, such people may (or may not) be partially correct, but they pollute their message because they can’t resist telling you how cool they are and, in contrast, how dumb you are. Which would seem to indicate a personality disorder. (Unless, of course, you don’t “buy into” the concept of personality disorders.)

      2. Gee, Lynda, I wonder which segment of BigPharma Avicenna was working for when he described manic depressive psychosis in the 11th century. Who was Soranus of Ephesus in the 2nd century working for? The conspiracy goes back centuries!

        Ordinarily I avoid responding to comments where all capitals are used. However, the stigma of bipolar disorder is bad enough without additional counterproductive suggestions that a syndrome that occurs in all countries and devastates many lives is imaginary.

    1. I too have bipolar disorder, I have lived at 57 north (northern Scotland) for the last 10 years. During our longest days it never really gets dark – you could read a newspaper in the garden at 2 am – and during the winter we only have about 6 hours of true daylight. This played havoc with me for the first few months (I arrived in August). Once I started using an eyeblind it helped a bit.

      However, what has really helped with the bipolar symptoms is turning Primal, in November last year, since Christmas I’ve seen a huge improvement, a totally unexpected bonus and I’m beginning to suspect there is a bio-chemical link between bipolar disorder and insulin sensitivity.

      Maybe Mark 😉 will come along with a bit more info on this one!

      1. When my blood sugar is on the way down from a high (not anymore since I’ve cut the carbs), I would get so irritable and mad at every little thing including myself. Blood sugar has a HUGH effect on mood.

      2. I too lived at 57N for nine years and I always had trouble sleeping during the height of summer. In the middle of June it never got darker than twilight the whole night (been at midnight) and even during the winter where it gets dark very early, the full moon sometimes made the skies barely darker than in summer!

  5. Holy crap, this could explain why I have so much trouble falling asleep in my college dorm: I have a nice dark loft, but my alarm clock is this bright blue monstrosity. I find I need an alarm clock because using my cell phone just does not cut it. Should I just settle for one of those red LED’s or does anyone know of any better options?

    1. I bought a battery powered clock that only lights up when you tilt it. It’s nice not having red, glaring numbers in my face all night. And if I need to know what time it is at night, I can easily find out. It also has an alarm clock, but I have a two year old that wakes me instead.

      1. What kind of battery powered clock do you have? I need to get a new one for my husband and have searched but can’t find one that tilts to light up. Only ones that are on continuously which I do not want.


    2. You could also go old-school and get an analog alarm clock that rings a bell when it’s time to wake up.

    3. I remember reading a while ago about an alarm clock that you wear on your wrist like a watch. You set it to a time range that you want to get up and it detects when you’re in the lightest phase of sleep during that time and wakes you then. Supposedly it’s less stressful than being woken from a deeper sleep, which makes sense I guess. Can’t remember the name of it, sorry, but could try googling it. Not cheap though, as I recall.

      1. It’s called the “sleeptracker” and I have an older one. It works very well and I wake from a nice light sleep. Gone are the days where I am wioken up right in the middle of a deep sleep and spend the rest of the morning grumpy and tired.

    4. I just cover the face of my alarm clock with a heavy towel or washcloth. Works great!

    5. My alarm clock has red numbers, but I put it on a low shelf next to the bed, almost on the floor. If I want to see the time, I have to prop up on an elbow and look down at it.

      And I never set the alarm. I use a lamp with a 60 watt incandescent bulb on the far side of the room, with a lamp timer to turn it on and off.

    6. I have an alarm clock/ cd player & an iPod dock by my bed, both with bright blue displays. I bought some cheap red photographer’s gel samples & overlaid them on the light-emitting areas. Amazing difference! Now I can have my sounds & sound sleep too!

  6. This really explains why I have a harder time sleeping (generally) when my cell phone is face up on my nightstand, it constantly emits a low light. How weird.

  7. Hmmm…I might have to ditch the alarm clock I got for Christmas with huge, bright blue numbers on it.

  8. i believe in this so strongly! so much so that after it gets dark, i put the laptop away and dim the lights in my living room until it’s my “bed time” my bedroom has no light in it and it’s a perfect sanctuary! i also feel like i’m one of the few who do not have a tv in there. the bedroom is NOT a tv room, it’s your place of rest!

    1. misa we don’t have a TV in our bedroom either, and likely never will! We’ve talked about it a few times, and have already decided that one TV in the house is enough.

    2. thats cuz ur poor and cant afford more than one , get a better job pussy

  9. Years ago, I read about the glowing numbers on alarm clocks disturbing sleep, so I have since turned the clock away from me at night time, and it really does make a huge difference. BTW, having even dim light on during sleep has also been proven to be detrimental to long-term eyesight.

    1. Really? Do you have a cite for that? I do not believe that dim light during sleep has ever been proven to be detrimental to long-term eyesight.

    2. Problem with all these electronics, though, especially turned around to the back, is the EMFs they emit. Those will disturb sleep a lot.

      I use a windup alarm clock, Big Ben. And if we were really getting enough sleep to begin with, we would not need an alarm clock to wake up at all.

      I have read that the way to resume getting proper amounts of sleep is to sleep til you wake up – usually people have to use vacation for this – and keep doing that until the sleep debt is paid off. Eventually, a person will wake up earlier, more in line with daylight, as the post above indicates.

      1. yes, if we’re awaken up by any external forces (alarm clock, phone ring), then we really don’t get enough sleep.

        sleep is a weird thing that we can only pay debt; we can’t store it when we’re not sleepy & withdrawl it later, like food & drink.

        but sleep until naturally wake up does work for people who have DSPS tho.


  10. So what if I change all my lights in my house for those yellow/orange “bug” lights of a lower wattage?

    1. I don’t think you’ll have to do that. I picked up some 13 watt “whirlie” bulbs which said they were “soft white.” Really, they’re yellower than an incandescent bulb. Equivalent to a 60 watt. I put one in the reading lamp over my bed last night, and was very struck with the difference. I thought it would be too dim, but I read a book without trouble by it.

      1. I forgot to mention something else.

        In the kitchen, I have deep yellow walls between the cabinets and the counters. I just bought “rope lights”, which are quite yellow, and I’m mounting them under the cabinets, one rope on each side of the sink. In the evening, they give enough light to putter around, and to have a background to the TV, but the room is bathed in a dim yellow glow, very soothing.

        I may try getting one of those orange TV filters as well. The rope lights draw 8 watts apiece. They were intended to be Christmas lights, so they plug right into house current.

  11. It’s funny, but since starting PB 14 days ago I’ve been going by a “lights out” policy after dark, and it’s helped my sleep immesurably. I was just doing this intuitively. When I get home at night, I only turn on the lights I need for a specific task, like washing the dishes, or cooking something, or a small reading lamp to read. I websurf in the dark (probably not the best thing ever) and now have no trouble falling asleep. Before I would have to take melatonin or lie awake for hours. The change has been very dramatic!

  12. When I saw this headline I immediately scrolled down the page to see if you had mentioned F.lux. I can’t endorse F.lux strongly enough. It has had a huge impact on my quality of life since I installed it.

    1. I installed f.lux yesterday after reading the article!

      Yesterday evening, for the first time in living memory, I spent a couple of hours on the computer, and by 9:30 p.m. I was bored with the computer and wanted to curl up with a good book in bed. By 10:00 I was ready to turn out the light. I had read years ago in “Lights Out” that sleep before midnight is worth much more than sleep after it, but never was able to get to sleep until almost midnight.

      This f.lux program is WIZARD! Mark gets a real vote of thanks for mentioning it!

      I’ve also decided not to watch TV after dark except on Saturday night. And I changed the reading light above my bed for a “soft white” compact fluorescent, yellower than an incandescent bulb.

  13. It’s great to see some recognition for the importance of circadian rhythms. I did my MS in a circadian physiology lab, and am now doing my PhD work next door to the guy who discovered melanopsin. Light is very important (but you have to take the light intensity WAY down to make a significant difference), but you would be shocked at how much feeding patterns can play into sleep cycles as well. Even subtle fluctuations in temperature can make a big difference. Of course, it is mostly impractical for the average human to take those things into daily consideration.

    1. Justin,

      Can you provide more information about issues that affect sleep? It sounds like you are working right next to a world class researcher and aren’t doing shabby yourself! We should take advantage of this. Everyone here is jumping into changing lightbulbs… and no one replied to your post.

      Can you provide more detailed responses to Mark’s article? Are there other ways to get better sleep? etc.


  14. One sleep related word that I really like is Suprachiasmatic Nuclei, or SCN for short. That’s the region that is taking all the light waves in and telling your brain to either take a break or wake up.

  15. Fascinating stuff Mark. I always love the variety you bring to MDA!

    For a long time I have been strict on keeping light levels low at night – I’m really sensitive to it and thought I just had paper eyelids or something. When I’m sleeping in a new room, I always have to cover LEDs if I cannot turn them off. I think some of it is psychological, because then I can relax but you have given us the sciene behind it!

    I even have 2 pairs of curtains in my bedroom to try and block the streetlight. I have slept in blackedout rooms before though and the lack of natural light in the morning just makes you feel groggy! So some light is good to wake your body naturally and gradually 🙂

  16. What about the lunar cycle? Some people think that it’s good to expose yourself to varying degrees of moonlight, as ancient people were. It’s supposed to regulate your menstrual cycle if you have one. I can’t really block out all the outside light when I’m in my city bedroom, but in the country I can. Still, in the country, moonlight streams in on some nights.

  17. I know when I dont get enough sleep (especially if i accidently leave my laptop in the bedroom and the charging light is going on the whole night) I get super grumpy! Now ill try to cover all lights in my bedroom, lets see if it helps.

  18. thanks for the link f.lux!! i just installed it cant wait to see it work around 9pmish, although i plan on being in bed close to then. i was reading a few excerpts from the book lights out, which i ordered online yesterday along with a copy of mark’s book (finally), and the vegetarian myth. 40 bucks delivered for 3 books what a bargain! ill never shop at b&n again, went in and they didnt have any of the 3. in fact vegetarian myth didnt even show up in their computer search!
    anyways i was very happy to find this as the blog of the day here!

  19. Sleep is incredibly important to our overall health. I agree with the idea that artificial light may be as bad as artificial foods.

    One of my goals in life is to find a community that mandates all lights out at night besides candle/fire light. There is a place in New Zealand that is like this. The stargazing must be absolutely amazing.

  20. Great entry! I would add that it’s not just the blue light but also the electromagnetic radiation that can disrupt sleep –never mind all the other things it’s doing to our bodies.

  21. My husband and I have been wearing ‘Blue Blockers’ for two weeks now – starting around 8 pm. Now they’re not the coolest looking things in the world, but the effect on our bodies and minds is incredible. We start to ‘shut down’ within a half hour of wearing them. F.lux – as great as it is – matters even less because I suddenly can’t muster the energy to look at the computer any longer. Where we were once night dwellers, never getting in bed before 12, we are now solidly asleep by 10 every night. Great, timely post Mark!

    1. In fact it was my (the husband) comment on Paleohacks that had the link to the orange safety glasses.

      I have to say I wouldn’t be caught dead outside the house with the glasses on and avoid standing near our windows where our neighbors could see us while donning them. They have more stylish, and more expensive, blue blocking glasses at

      The effect the glasses produce is very dramatic. It was definitely worth the $10 just to experience it.

  22. This line is very interesting: “Reddish light from fire (our formerly primary source of nighttime illumination) has little to no effect on melatonin production, so sleep wasn’t disrupted when we relied on fire.” When hanging out around a fire (at my buddy’s ranch for example – a huge bonfire), it’s relaxing, mesmerizing, and therapeutic. Maybe the reddish color of the fire has more to do with it than we ever imagined. Very cool and interesting info.

  23. I downloaded F.lux and it should activate in about 20 minutes here. I also found that an old pair of cycling glasses have an orange lens I can use in place of the regular one, so I am re-activating those glasses just to see what happens.

    I wonder if F.lux helps at all if you are still exposed to tv, and regular lighting in the evening, but don’t have any special glasses on? It just seems too easy to get 95% of this right and have the 5% I miss negate all of my efforts.

    1. Before we got our safety glasses I tried a pair of regular sunglasses I own that have a orange/amber hue. They didn’t really have any effect.

      I bought those glasses Mark linked to because I came across them here while reading up on the effects of blue light:

      Also, you can see they are the same as the pair in the pic at even though that site doesn’t sell them.

      When put these on things that are very blue appear almost black because they block a large percentage of the blue light.

      My understanding is that few minutes of artificial light can negate the effect. I haven’t experimented with wearing the glasses for a while and then taking them off, though.

  24. I read Lights Out several years ago and have always been concerned about all those appliances with lights emanating out of them. I am now living alone after several years and it is so difficult for me to sleep in a pitch black room, I start hearing all kinds of wierd noises, but I know when I do turn the lights off and the computer off, turn my alarm clock around and my cell phone off I feel better. When I don’t get enough sleep I am like another much older and decrepit person. I am definitely trying some of the items mentioned.

  25. Last month (partly to keep the cold out) I took a very heavy very dark colored blanket (not very decorative) to cover the windows in my bedroom.

    Since doing so, I sleep better because the room is pitch black. I also noticed that I sleep longer on the weekends averaging 8-9 hours instead of 5-7.

    Also, every night, my phone shuts down at 10pm which is my bedtime so I won’t get the annoying text from someone who really has nothing to text about.

    1. If you cover all the windows so it’s pitch black, how do you ever wake up?? Don’t you need that sunlight coming in? If my room was truly pitch black I think I’d sleep till noon.

  26. Is there anything like f.lux for room lights?

    Candles are not a practical long run solution for me, and I’m concerned about the fire risk as well as indoor air pollution. Going with no artificial light would be ideal, but it’s difficult to wrap everything up by sundown, especially when there are others in the house.

    Therefore, if there were a way to automatically switch all overhead lights to ‘red mode’ after sundown, it would be an easy way to correct melatonin deficiency.

    1. If you get the “soft white” compact fluorescent bulbs, really, they are quite yellow. I’m changing over to them exclusively in rooms where I spend evening hours. Also trying the orange glasses. “Chromalux” bulbs also have a lot of red in them, and radiate heat, so they’re nice to use in a cool room in the winter.

  27. I’ve been an advocate of preserving sleep in order to enhance health, manage weight etc for years but hadn’t heard of the whole blue vs other light thing. Thanks Mark, very interesting.
    I have to say, I suffered insomnia severely for 3 years and one thing that did help (among other methods) was to force myself to cull the TV and computer a couple hours before bed. I think if people realised how much lack of sleep affects every element of their metabolism, health and wellbeing and not just their energy then they’d be far more motivated to do something about it.
    In my mind a sleep debt is one of the primary reasons for obesity and poor health.

  28. Great post — glad to see this topic getting more attention. Sleep deprivation and excess sugar seem to have near identical negative effects on the body and endocrine system.

    Thanks for the mention! I’ve just posted a detailed description of our “Month Without Artificial Light” experiment on my blog. There were both positive and negatives. The New York Times article I link to and quote from is a must-read for anyone interested in this topic.

    1. They appear to be much more yellow than the orange cooper safety glasses. The orange cooper glasses block something like 90% of the blue light.

      I didn’t get much of an effect from some sunglasses that were fairly orange so I don’t think driving glasses will cut it.

      The safety glasses are only about $10. If your looking for something more comfortable or stylish you could give the cooper’s a shot first to see how it works for you.

      1. One thing strikes me, if they are night drivers surely it wouldn’t be safe if they were blocking light that might keep you awake, as being awake might be quite important when driving!

  29. I read a hypothesis of evolutionary a that small percentage of our ancestors were natural owls so they could guard others against predators during the nights.

    then i must be a descendent of them. haha (light therapy does not seem to work too well for me as my circadian clock is not very sensitive to light.)

    1. I’ve read that hypothesis too, Brain Rules? I hope it’s not true or I may be screwed. I’ve always had trouble falling asleep.

      The one thing that has helped me fall asleep is heavy exercise during the day. Though I usually end up ‘napping’ for 2-3 hours right after a long surf session and that makes me stay up later lol

      Thanks for the suggestions Mark!

      1. hi, Dan,

        are you insomniac or you’re just not tired?

        i am not insomniac. i can fall asleep in 5-10 min if i’m tired (which is between 1 & 2 AM)
        i am just not tired at all. so it feels very wasteful to me to toss in bed during my prime time when i feel most productive & alert. (i think it’s called “delayed sleep phase”. maybe you have it too.

        I just downloaded f.lux. i hope it works. like i said, light in the morning does not wake me up. i could sleep in a bright room in summer until noon. exercise also does not work for me.
        i have also learned that napping is a bad idea.

        at least my DSPS is not too extreme like others, so my constant “jet lag” is ONLY 2 hours for standard time (or 3 for DST).

        good luck.

  30. My 6 year old is scared of the dark and insists on having quite a bright nightlight… should I be putting a red bulb in it? Will that help?

  31. Thank you so much for this article Mark. Definitely an Aha! moment for my fiance who has massive trouble falling asleep and coincidentally is on a laptop until late at night.

  32. Has anyone tried to change out all of their light bulbs to non-blue light emitting ones? That was the first thing that came to my mind after reading this article..thanks Mark!

    1. I just bought two yellow “bug” lights at Lowes. I check there and Wal-Mart but neither had one less than 60watt so the 60 is what I got. No amber night-lights either. I’m trying those bug lights out tonight to see if I should replace more of them. (I tried candles last night but the parents were over and we needed the lights and then later as I’m heading to bed the wife turned the lights on to get ready for bed which made me angry.)

  33. I put F.lux on my computer, and now actually get sleepy during my late-night Stumble/blogging sessions. Wonders for my sleep schedule.

    Great post!

  34. Thank you for posting this! Your explanation of the types of lights is so much more helpful than the typical ‘don’t sleep with the tv on…don’t keep your cell phone next to the bed’ you see in tips for a good night’s sleep articles.
    I downloaded f.lux last night and began yawning within minutes (okay, it was seconds!) and I went to bed early. Also for the first time in years, I tried and succeeded at falling asleep without the tv on. Thanks again!

  35. I also found that Vitamin B12 status matters a lot to melatonin production. (People without enough Vitamin B12 don’t make enough melatonin.) Older people often have trouble absorbing Vitamin B12.

    When I tried the methyl form of B12 (under the tongue) I started sleeping like a log! And much longer at night. The bedroom has to be really dark, of course.

    I prefer the Jarrow brand of methylcobalamin, but others no doubt are all right as well.

    Vitamin B12 also improves small muscle coordination. I read that Olympic marksmen take methyl B12 because it eliminates a tiny tremor and improves their scores.

    Here’s to good sleep!

  36. After looking carefully at the melatonin study statistics, It seems that the sample size was extremely small: n30 to be even more convincing.

  37. I JUST INSTALLED FLUX AND IT IS AMAZING! I seriously just spent ten minutes sitting here turning it on, turning it off, turning it on………..

  38. For some strange reason, I can’t get Flux to download. I think maybe it’s our apartment complex’s firewall that I can’t get around. Can someone e-mail me the .exe file so I can install it?

    supercanid (atsign) gmail (period) com

    Thanks in advance!

  39. I have not purchased one of these (but plan on doing so), but for those considering replacing their alarm clocks you may like this:

    It’s a “daylight” clock that simulates a sunrise, so it attempts to wake you up by assisting with serotonin production rather than with a loud noise. I really like the idea of it since I room in a basement right now, so I have no way as of current to wake to sunshine on my face. Saving for it!

    1. That looks expensive! Cheap people (like myself) could perhaps attach a cool-temperature (i.e. florescent, LED) light to a wall socket timer for almost the same effect.

  40. The Candlelight trick seems to work well. For more info on daily health including diet and tips see our blog.

  41. I installed Flux but now nothing happens when I click on it (I want to change the settings) — anybody else having this problem? There are no answers on the Flux page, tho many people have also asked the same question there.

    1. go to your bottom right hand icon tray and click on the icon there and see if that works.

  42. I’m a little confused. What is this saying specifically about incandescent bulbs? Are they considered red? Or blue? All I see mention of specifically is LED screens, TVs, etc.


  43. Hi Mark!
    Great post as usual. This doesn’t have to do with light, but does have to do with sleep.

    I wanted to add that anyone who supplements with vitamin D should take it in the morning only

  44. Continued from above…

    oops, I hate when I hit submit by accident!!

    Anyway, I had read, I thing on Dr B.G.’s blog (Animalpharm), only to take vit D in the morning as it simulates daytime to our bodies. (makes sense).

    Since I started supplementing in the morning only, my quality of sleep has been much better. I used to wake up after about 4 hours (around 2am,) and not be able to get back to sleep. Now it only happens occasionally, so I am trying to make the room as dark as possible, and will try to keep lights dim after sun down as well.

    One more tip- keep some water handy OUTSIDE the fridge if you wake up thirsty. I can’t tell you how many times opening the fridge door in the middle of the night woke me right up.

  45. Can you get the orange safety goggles at a local store? Or only online?

  46. I’ve been trying the candle light approach too since reading the posting and it definitely has a calming effect. Here in northern Scotland we have very varying sunsets, due to our northerly lattitude. At the moment it is fully dark by 1830 and the first evening I just didn’t turn any lights on at all, just lit candles – I was on my own so suited myself. It felt good and the f.lux made a massive difference to my eyes.

    Since the we’ve been using minimal light for the last couple of hours before bed just using a bit more earlier in the evening to get the chores done.

    I have to say I came to the conclusion that Grok probably didn’t play Scrabble, at least not during the evening, as candlelight wasn’t really enough to see the tiles and the board properly (we have a darkish coloured set and wooden tiles!). However, my husband, not wishing to disrupt my plans silently disappeared and returned wearing his miner’s headlamp set to infrared setting, I don’t think I’ve laughed so much in years, Primal Law 7 me thinks.

    Anyhow feeling sleepy at around 10 with less lighting in the preceding hours. Now just need to work out what’s waking me around 2:30 am every night and then hourly thereafter, think it might be the emissions from my digital clock radio which although now covered isn’t switched off, doh …

    If this works we’ll need to start actually shutting our curtains to block out the daylight a couple of hours before bed time as we approach mid summer to keep some kind of pattern for sleeping.

  47. “It’s all the same to our bodies, because for millions of years blue light meant daylight, not a late night blog comment section or reruns of The Daily Show.”

    Suggestion: Make a script that sets your blog to monochrome red if the reader’s browser indicates their local time is ‘night’.

  48. Re: using candle, kerosene et al as an alternative to the electric light bulb….

    there is a risk…..

    the output from these sources adds to the toxic load the body is subject to in our modern society…. what all they are is another subject, but when the total toxics exceeds the body’s ability to eliminate them, we come down with one of the adult-onset degenerative
    diseases, cancer among them


  49. Hi there,

    I looked over your blog and it looks really good. Do you ever do link exchanges on your blog roll? If you do, I’d like to exchange links with you.

    Let me know if you’re interested.

  50. Hi there!

    As long as i can think i have trouble getting to sleep.

    I want to exchange my normal bulbs to bulbs that are good for sleeping.
    Now i am wondering what the right bulbs are:
    – normal ‘nightlights’ in the store (has it blue light in it?)
    – LED – lights – i guess they are also blue. Red LED lights?
    – lightbulbs that are red (normal bulbs with red covers)
    – only lights from

    I find it confusing. And i am starving for info. Are there books? Is there any forum or something that talks about this? The blue-light thing is pretty unknown, is it?

    Thanks for the help!

  51. I usually fall asleep in a few minutes in a dark environment but in a light room and with some sort of noise it takes maybe an hour for me to fall asleep.

  52. Wow. I am now fully aware of just how much I’ve been screwing over my circadian rhythms.

    Thanks so much for your post! I was reading about circadian rhythms at two in the morning on my laptop, then wondered why I was having all those sleep problems. =D

  53. Hi adrenalin often wakes us up – in an effort to maintain blood sugar – the body will release this – so we do not die – often times eating a piece of fruti before bed, and/or if we wake up in the middle of the night – a piece of fruit then – we can go back to sleep – the time between our last meal and breakfast quaifies as starvation – so eating a food that balaned blood sugar beofre bed will help. Of course if the mind is spinning – learning to turn off the mind by concentrating on breath – helps also

  54. I cannot sleep even if there is a loptop running in my room. That’s really bad as I see some people sleeping on a bus in the middle of the day, how can they do that?

  55. “If you want to try a somewhat extreme experiment you could even wear orange safety glasses at night.”

    That was something new for me. Checking that glasses right now.

  56. Watch out for heavily scented candles, etc. They often emit toxic volatile organic compounds. Look for the clean-and-green ones if you’re planning to burn ’em.

  57. i’ve got a couple of questions-i just saw these bedside ott reading lamps that have led lights-i’m wondering how these would affect melatonin?
    also, how about these crystal salt lamps-wondering how the light from those might affect melatonin?
    i’m trying to figure out what the best light for reading right before bed would be-candles aren’t quite bright enough!

    1. I have a desk lamp beside my bed with a florescent “bug-light” yellow bulb in it. Warms the room up like a fire and plenty bright enough to read by.

  58. Turning on a bedside lamp at nighttime can block the stimulation of the pineal gland. This results in a continuous drop in the level of melatonin secretion. Exposure to light can help control the production of melatonin. Light therapy can be used to effectively regulate the levels of melatonin secreted by the pineal gland. This type of treatment can be used for treating sleeping conditions like insomnia or jet lag.

  59. I spent nine months minding a farm house, without electricity: candles & gas cooking were what I had. two hours after sunset: nothing better to do than sleep! Of course, my days were filled with hauling water, long walks to pull noxious weeds & repair this & that around the place, or just exploring. Presently, I use 4 & 8 hour candles in candle lanterns. I also recommend three candle power for reading by. AS fro keeping the bedroom totally dark: only if you have street lights, which, IMHO, ought to be turned off at 10pm.

  60. Thanks for this article! Ever since I started using candles at sunset, I’ve gotten lots more sleep! And now that I’m sleeping better I’m less tired, I have more energy, my hair has gotten more shiny and my vagina is much softer! My husband couldn’t be happier!!

  61. That would be cool to be able to adjust our smart phone’s screen colors. You did see the post about the alarm clock app that senses your stage of sleep, yes?

    There is one for Android too (my phone) but I don’t remember the name now. You all have motivated me to seek it out again.

    One of my biggest problems is waking in the wrong stage of sleep. If I am woken right after dream stage it takes me 5 hours to wake up. And try to wake me from a dream… good luck; you’re on you’re own! But if I wake up from a light sleep, it’s like I was fed Friskies that day.

    I wonder if that app would do any good, though, since the phone has to be touching or very near you. Might as well sleep on top of your computer for all the EMF’s and radiation. My speakers go nuts when my phone’s trying to find a signal. Airplane mode would probably help a lot though.

  62. Thanks a lot for all of your suggestions! I have learned a lot and am now typing on an orange screen, in a room with some serious romantic lighting. LOL!

    As an added bonus, I discovered previously that sunset-ish colors on my monitor make text reading much easier, and cut down on eye strain immensely — particularly for LCD screens. I haven’t tried it on a CRT yet. It sucks for movie watching though. I choose to manually control the F.lux software for this reason. For text reading, I turn my backlight very low, and even more orange than F.lux does, using the monitor’s manual adjustments. (I am using a 32″ HDTV as my monitor while lounging, BTW.)

    Also, here are my previous ATI Catalyst color settings for text reading. F.lux overrides these, but in case it’s not your thing:
    (gamma, brightness, contrast in that order):
    Red: 1.00, 0, 100
    Green: 1.10, 0, 80
    Blue: 1.00, 5, 36

    Not sure about Nvidia graphics cards yet. I’ll post back when I get one in a couple of months.

  63. A few more tips I’ve found helpful:

    Peach light bulbs not only help get the blue out, but are wonderful for entertaining guests. Everyone looks better. You can also paint energy-saving flourescent bulbs with non-toxic paint from the craft store. They last for years and they’re luke warm. Try splattering the paint if it ends up too dark when coated. I’ve made “make-up” lighting for my bathroom this way (a.k.a. day (blue & pink,) evening(peach,) office (blue, green, and pink.))

    Try using plug-in timers on lamps and/or plant lights to create “F.lux” for your home.

    When I get off the computer or TV and read before bed, even with an ebook reader or cell phone, I fall asleep on time and get much better sleep. Admittedly, though, I have my ebook text set to yellow on a brown background. Intersting that!

    Lastly, I either use a loud box fan or the White Noise selection at to drown out noisy neighbors, or just for particularly sleepless nights. The pink noise is great for covering voices. The White noise is nice and reminds me of an airplane ride. The Brown is very nice at first, but strangely this and the pink keep me awake. I’d like to find a grey noise app somewhere.

  64. Oh! you can mix the 3 types of noise at too. Just open 3 browser tabs or windows and they’ll play at the same time. I “think” this would work on the new smart phones with Adobe Flash player too. I’ll try it.

  65. Last post. Sorry for hogging the spotlight.

    The reason I suggest all of these techy solutions is because I live in a studio apartment where I am always in the same room with my computer. The computer must stay on 24 hours because it’s my DVR, and has shows scheduled to record at all the time. So far, I can’t even sleep without the sound of the computer fans going. But you all have gotten me thinking about trying to work something else out.

  66. I just found an orange “night mode” screen app for Android! Someone here asked about this and I’m so pleased to have found it.

    It’s called Chainfire3D. It’s actually a graphics driver which has the “Night mode” setting inside when you open it…. The bad news: You must be rooted, and you must have a very new device — 1Ghz processors only. The good news: It has several screen color options — Salmon, Red, Amber, Green and Blue. And it has a homescreen shortcut just for toggling night mode with one touch. Not only that, but it’s original purpose is to speed up your phone while playing high-end 3D games. I also plan to use the Blue screen mode during the day to see if I feel more awake.

    What an excuse to treat yourself to a new gadget! :->

    This was my last blue source of light that needed to be eliminated before bedtime. Thanks to all of the advice here I should be able to get on a regular sleep schedule now. Would not have known the value of this app without you all. Thanks again!

  67. It’s currently 2:14AM and I’m having trouble sleeping…again. After stumbling across this article I believe some of my sleeping problems are due to my alarm clock which displays the time in bright blue numbers. In the past I had come to believe that I fell asleep faster when facing away from my clock but in the back of my head I didn’t see any reason why this would be, however I guess that suspicion was totally correct!

  68. THANK YOU for the f-lux idea. I’m going to insist my 16yo daughter install on her laptop. She loves her laptop (bought it herself with her own money!) but she uses it ALL THE TIME, and it’s in her room. She has memories of being 3-4 and wondering why everyone else in the house was sleeping but her. These days, she might fall asleep by 3am. Of course, I’ve mentioned Primal/grain-thing to her, but she LOVES her grains too much. But, hopefully, adding this free little doo-dad to her laptop might have a positive effect on her sleeping.

  69. I enjoyed this article and all the comments and posts. I’ve been basically primal for 4 years but I am SCREWED because I work nights. Always have (tech support, we’re talking the bulk of 20 years) so I cannot implement most of these wonderful suggestions. I’ve studied circadian cycles, shift work, etc., and am doing the best that I can. I have a very dark room, take melatonin before going to bed, take my supplements when I get up, and sleep very well during the day. I think I am one of those nocturnal people who were sent to protect the others during the day because being up at night is so natural for me. Whenever I have to come into work during the day for training, etc., it’s miserable and so hard to stay awake, but I am fully awake all night without caffeine or drugs. But am I *really* an anomoly? While my health (other than asthma/allergies) is close to perfect (you should see my blood counts!) I’ve gained 12 pounds or so this year that will not come off though I have not changed my eating habits, etc. When I’ve written to other primal “gurus” I am dismissed with “quit working nights” like it’s that simple. For one thing, I love the benefits of working nights, not the least of which is the shift differential that goes along with it; after losing a comfortable job I held for 20 years I’m stuck starting over again so I’m making the most of where I’m relegated presently. So am I doomed to never have the best health I could because I am a night owl? Or am I already there (since being a day person is so foreign)? I have even thought about taking a day shift to see if that would help me drop these pounds (I stayed in my 5# range for 3 years) but I can’t afford the pay cut so that’s not an option at this time. I am actively looking for another job and am open to working days though I know my mindset is not ready for it. But my motto is “If you continue to do what you’ve always done, you’ll continue to get what you’ve always gotten” (and yes, I sell that on a t-shirt!) so if I can afford to change shifts, perhaps I will. Thanks for reading.

  70. This is bull crap. I have been sleeping with a light on since I was born, and I don’t ever have a problem. If you condition your body at a young age it will get used to how you sleep, with light or not. Obviously if you sleep with light off the entire time your alive, it would be difficult to get used to light on. For me, I find it extremely difficult to sleep with light off. I constantly wake up. It’s the same effects for people towards light on, just this time, it’s off.

  71. After having sleep problems for over a year, I read about the circadian rhythm, blue-sensitive ganglion cells and reading about every blue blocking device around, I ended up with the glasses.
    As I have a family, I didn’t want to use blue lights as it would affect everyone and candles are too dangerous with kids around. I tried commercial sunglasses, but blue objects still look blue so they weren’t very effective.
    In the end I made my own which worked well for me. After about 30 mins I could feel myself relaxing. By bed time I was ready for a good kip.
    I’ve made 50 pairs of these as cheap as I could and am selling them on eBay at a VERY low price here:

    If they go well I’ll make more. If they don’t I’ll drink beer and watch the telly like normal people 🙂
    Best of luck


  72. Guess shift workers don’t fit into your precise plan. While I agree there’s a needed importance in quality of sleep, the comments appear to make this overly complicated system just to get a natural sleep.

  73. 301 Moved Permanently I was suggested this blog by my cousin. I’m not sure whether this post is written by him as no one else know such detailed about my problem. You are incredible! Thanks! your article about 301 Moved PermanentlyBest Regards Lisa

  74. I like the helpful info you supply to your articles. I will bookmark your blog and test again right here frequently. I’m rather sure I will learn a lot of new stuff right right here! Best of luck for the next!

  75. I’ve had chronic insomnia for the last few years. It has been so severe that I spent hundreds of dollars seeing family doctors and even a psychiatrist. All the professionals threw prescription after prescription at me- sleeping pills, anti-anxiety meds, etc. You name it, I’ve tried it. I don’t even sleep with the sleeping pills. It has been so depressing and discouraging. I’ve followed all the right procedures recommended for good sleep hygiene. Don’t use any caffiene, exercise a lot during the day,…. I have been looking and re-examining why this came to such an ugly head about 3 years ago. I was about to be laid off from a job I loved for 17 years so I accepted that it WAS anxiety. But after reading your article and the comments, I have gone back and discovered that about that time, we bought a large flat screen tv. I do try to read before bed as opposed to watching tv since I was aware that could be an issue. But I have been reading in the same room while my husband has the tv on. I’m now experimenting that perhaps it is the blue lights from the tv? I read the comments and ordered a cheap pair of blublocker glasses and will use that as well. Can anyone tell me if there would be a difference in the amount of blue light from a large flat screen tv versus our old small tube tv?? Thanks for your article and all these comments and suggestions. I pray that this is the answer to my insomnia and that I can get off these horrible pills and their side effects. Thanks again.

  76. Can anyone recommend a blue blocking sunglass or eyeglasses. I’ve researched on-line and there are several companies and choices. Still, I would like to buy eyeglasses/sunglasses that someone has found to be very effective- I don’t care about style either! I want what works!! Thanks!

  77. I have a Himalayan salt lamp that softly lights up the open plan kitchen dining and lounge till I can get candle holders to put on the wall, safely out of harms way. It is great when we get up in the middle of the night for a glass of water.

    There are all sorts of beautiful ones that look like works of art that use tea light candles which are pretty safe in the glass holders.

    Or better yet backed with a mirror to reflect the light back into the room therefore needing less candles.

  78. I found anti-blue light glasses at an optician the other day and bought one. Does anybody know how effective they are to you?

  79. Hi Mark,

    I’m doing research on how blue light affects sleep for my blog ( and found this website. Wow, I’m really impressed with your writing. Thanks for all of the good info. Maybe we can collaborate some day. Maria

  80. I am a TV repair Tech, my client told me about a study a university did on the subject of watching anything with a flourecent light including lcd tvs (but that was due to the flicker rate of them which is very fast and I dont see how that could be an issue) But, It lead me to your article, great write up! Do you think adjusting the tv’s warmth of picture would help those who just love to watch tv in bed ?( movie mode usually reduces blue output, makes all the white colors more tan )

  81. After being diagnosed with PTSD two years ago,(also an alcoholic, mickey) I have found that a red light helps me sleep and stay calm. Im not sure why but it it reminds me of being in the belly of a submarine…a very safe place. There are still nightmares accompanied by cold sweats but when I wake and see the red light, I become calm almost immediately. Mickey, if you are still reading this, I want to bring a place called the “refuge” to your attention. They did wonders on my trauma issues!

  82. Awesome blog you have here but I was wondering if you knew of any message boards that cover the
    same topics discussed in this article? I’d really like to be a part of online community where I can get suggestions from other experienced individuals that share the same interest. If you have any suggestions, please let me know. Thanks!

  83. This is how I (age 79), after years of
    worsening night time sleep,am now continuously sleeping deeper and longer, and furthermore, have virtually eliminated urinary wake-ups. Originally started to deal with excruciating pain due to onset of hip arthritis, am now totally pain free following six months of “earthing”.
    For full information, go to:

  84. We manufacture the lamps and glasses for the UK and European markets. Reports from customers say 68% of them using lamps or glasses can gain effective control of sleep dis-orders. The high specification products allow maximum reduction of Blue Light in the spectrum. best regards to all sufferers. Ronfell

  85. I have a cheap LED flashlight that has a red only feature, I would prefer that to a candle. Safer too. Any comments on that strategy??


  86. has anyone ever heard about that blue light is bad for our eyes? They’ve launched special glasses blocking blue light to minimise the exposure to it during the day. So what is it now: Blue light on or off?

  87. Thanks for sharing your thoughts. I really appreciate your efforts and I am waiting for your further write ups thanks
    once again.

  88. Just letting you know, there are also spectacle lenses that have “Blue Control” coatings incorporated, which filter out these blue emissions. Great option for computer users to have this option, which looks just like a normal lens.

  89. Great post!

    Question for everyone: I work a shift from 3:00 AM – 11:00 AM. I get roughly 5 hours of sleep at night and then take a 3 hour nap in the afternoon to maintain the number of hours. I’ve recently picked up a pair of blue blocking glasses to use at night to try to optimize my melatonin production at night for those solid 5 hours. Should I continue to wear them for the early morning hours (3:00 AM until sunrise) where it is still dark or use regular light to wake myself up and halt melatonin production?


  90. I have a problem that if I do not read before sleep I can not fall asleep and therefore need to use a led light for reading in my bed. If I do not.. I can be in the dark for hours and I won’t get any sleep at all and mess up my cycle that way.

  91. Yes! This is actually a big issue btwn my wife and I. She says she needs to have noise on in order to go to sleep and usually its a netflix show on our computer. Before we met I never used any tv or radio or anything to help me fall asleep and I feel like I never get a good night’s sleep. I tried to show her articles about this very subject but she’s very stubborn and tried to claim that since it wasn’t the television but the computer, that it was ok. I don’t know what to do bc I do believe her that she needs the background noise to go to sleep but I also believe this is bc she’s trained herself to fall asleep to this noise and that if she could wean herself off this habit, she’d sleep better. She literally wants to have close to 10 hours of sleep a night and I honestly think its bc she doesn’t have good sleep bc the computer is on playing a show. I hate having these shows on in the background when I sleep. Any ideas of what to do? Eventually the computer does go into sleep mode, so its not like we have the blue light on all night. But I still feel like this is messing up our sleep.

  92. How can I save “ALL” this stuff? mind blowing to say the least??Thanks,,Cliff Gant(inventor)

  93. I have tried f.lux on my hand held devices, but on my multi screen PC’s I have found a new program pc sun screen to work really well. You can even change the time when you want to sleep as well as many other things.

  94. * For computers, there is software that adjusts the screen colors automatically to the time of day or room you are in. This one is free for Windows:
    * For Android phones, you can use blue light filter for eye care:
    * There is preventative eyewear that can be purchased in a yellow tint or clear tint usually from websites such as or
    * And finally, I found this article that gives some recommendations on how to protect your vision:

  95. I designed and implemented accent lighting forb use as general lighting, and limit the brighter room lighting for those occasional necessities. Since the only cool-white light inb use is the porch light, I don’t have much in the way of blue light impact. Yet, I still have issues retaining a dawn to dusk waking cycle. Point is, not everyone has the day-awake abilities. Some of us are cursed to sleep at night. Also, I have issues seeing red, but that is for another conversation.

  96. Can you… *sigh* can you willpower through blue light’s inhibitive effect on melatonin production and just “go to sleep anyway” because that’s “what [you] want to do”? Someone I know said they don’t know why they can’t get on a normal schedule, I said start with cutting electronics for an hour before bed cause that works for me, and pointed to blue light. They said–you know what, I give up. I give up on this person twice as hard as they have given up on science.

    This person can figure it out on their own.

  97. REM – I’m surprised no one has mentioned it in reference to this (excellent) article. From what I understand, each time you enter the REM stage throughout your sleep, it lasts longer and longer, and it’s the final stage, closest to waking up, that REM is the longest and deepest. (I won’t take the time here to explain the importance of REM on our overall health and well-being, and the consequences of not getting enough of it, but it is worth looking into for everyone, whether you have sleep issues or not.) When you are exposed to light in between the REM stages, the pineal gland resets and your REM cycle starts over, so you never reach the most important phase of REM. (Red light has no effect on the REM cycle, blue has the most effect.) Many people complain that they’re always tired, even though they got a full night’s sleep. This is because you will never be totally rested without a sufficient amount of REM sleep. Several years ago I started blacking out my bedroom window and turning all nightlights off before going to bed. If I need to use the bathroom in the middle of the night, I do so with my eyes closed, so that the light from the glass block window in my bathroom doesn’t disturb my pineal. That sounds so weird lol, but it is working so well. I do go to sleep watching some mundane show on my laptop, but I turn the screen brightness all the way down, and it goes into sleep mode automatically, so if I wake up during the night it is not giving off any light. Just before my alarm goes off in the morning, a bright fluorescent light that is plugged into a timer turns on, which simulates morning and gently nudges me out of deep sleep. One of the best things I’ve done is buying a talking alarm clock. It drives me crazy not knowing what time it is if I wake up during the night, so now I can press a button and the clock tells me the time, without exposing me to any light. It’s a little one on a keychain, it has an alarm, it was very inexpensive, and it has worked wonders. Amazon sells several styles. After reading this article, I will now pay more attention to the evening hours before going to bed. I will also make sure I get plenty of “blue” light during the day, and hopefully both my REM cycle and my circadian rhythm will be operating at optimal levels, making me even more happy, healthy and energetic. 🙂

  98. There is a new device on Kickstarter called Sleepion, which claims to help with sleep by stimulating your senses, i.e. smell, hearing and sight. As far as I understand, it emits light (2700K) during the night to imitate moonlight. This apparently will help you sleep deeper.

    As I’ve always been told to sleep in a pitch black room (and have experienced this to work better for me), I wonder if there is some science to their claim.


    From their website:
    The light imitates moonlight which regulates our biological rhythms, giving us a sense of security.

    “Light is characterized by its color temperature and luminance, and the optimal levels for sleep are 2700k in color temperature and 35% in luminance. This is close to the color of candlelight, and to the moonlight, which mankind has been gazing at since the birth of the human race.” (Professor Shimizu)

    Based on Dr. Shimizu’s research data, Sleepion’s light flickers like a candle and is as bright as moonlight, inducing a state of deep sleep once you fall asleep.

  99. These articles are very interesting, I am new to reading your blog and I have really been fascinated by all the content I have read, I am also starting a keto diet, I hope you continue to publish more articles, greetings from Peru.

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