How to Conduct a Personal Experiment: Biphasic Sleeping
It’s time for another edition of “How to Conduct a Personal Experiment.” Last week, it was the cold water plunge. Today, we’re going to talk about running a biphasic sleep experiment. First, though, I’d like to know: how are the cold plunges going? Are they, well, cold? More importantly, did you have any difficulties setting up the experiment, identifying variables, and choosing what to measure and track? This whole personal experiment stuff is likely new to most of you, and while there’s no real “wrong” way to go about it, there will be some initial difficulties. Be sure to keep us posted in the comment section.
Okay, on to the new experiment.
Biphasic sleeping is exactly what it sounds like – two-phased sleep. Instead of monophasic sleeping, which is sleeping in one big unbroken block of time, biphasic sleeping is broken up into two chunks of time. I wrote about biphasic sleeping last year, explaining how considerable evidence suggests that biphasic sleeping is actually the natural sleep pattern in humans. Before the Industrial Revolution, back when darkness meant bedtime and keeping the light on after dark required the consumption of expensive candles and lamp oil, people had far more exposure to darkness. They didn’t have iPhones, laptops, big screen TVs, or even lightbulbs. They had the moon, the stars, the campfire, or maybe – if their city had implemented them – street lamps that were really just candles in glass. And this shorter photoperiod resulted in a very different way of sleeping:
You’d get to bed shortly after darkness had fallen and sleep for several hours. This was “first sleep” (later mistranslated as “beauty sleep”). Sometime around midnight, you’d wake up. You’d putter around, read a little by candlelight (if you were literate and could afford candles, that is!), make love, get up and dance, check on the animals, talk with friends or folks in your tribe, think of stately pleasure-domes in a partial waking dream state… that sort of thing. In short, you would be awake and at least moderately active. You’re not a groggy, grumpy person here, fussing with your pillows, thrashing at the comforter, and agonizing over the alarm clock. You’re reasonably alert and cheery.
Then you’d drift off to “second sleep.” Sounds cool, right, but out of the realm of possibility for us living now? Maybe not.
Studies find that modern humans living in an technological permaglow of light will revert back to the biphasic sleep pattern when exposed to shortened photoperiods (from 16 hours of light to 10 hours of light), so the potential remains.
But very few of us are humans living in contrived study settings, and that’s what could make this one a little tricky. Ideally, biphasic sleep is effortless. It just happens. You wake up, read, talk, use the loo, or do something gentle for a few minutes or a couple hours, and go back to sleep without actively trying to make it happen.
That won’t work for everyone, not without active intervention and formal experimentation. Which brings us to the personal experiment.
But why biphasic sleep?
Mostly because I find the notion that we’re all “doing it wrong” when it comes to a fundamental aspect of our lives – sleeping – extremely interesting. I mean, it’s not like it hasn’t happened to us before (diet and exercise, anyone?). It’s not out of the realm of possibility. I’d even say it’s fairly likely that we’re getting something wrong when we sleep, seeing as how 60% of Americans between the ages of 13-64 report having a sleep problem almost every night, whether it’s waking up feeling groggy or waking up too early. Even those of you who are clued in to the whole Primal thing might find it helpful to explore another way to sleep. In my last post on biphasic sleep, I referred to it as more of a thought experiment than anything else, but today I’m recommending people formally attempt to integrate it into their lives, if only for a month or so.
That said, is there more than one type of biphasic sleeping? Sure:
Natural biphasic sleep
This is what I call normal human biphasic sleep – two four-hour blocks of sleep broken up by an hour or two of wakefulness in the middle of the night. Easy to understand, if hard to implement.
Modified biphasic sleep
This is the kind of biphasic sleep that lifehackers employ. They’re not really interested in anthropological or evolutionary arguments for sleeping a particular way; they want to save time and get the minimum dosage of sleep that confers the maximum amount of benefit. They see sleep as a waste of time, albeit a necessary one. From what I can tell, lifehackers typically sleep for a 4.5 hour block of time – say, from 2 AM to 6:30, which allows them to stay up late, get three, full 90-minute sleep cycles in, and rise early to greet the day. They follow up with a 90-minute nap sometime in the late afternoon, which gives them another 90-minute cycle and enough energy to make it to the next sleep block.
Sidenote: I’m somewhat skeptical of these shortcuts when it comes to sleep. From what I can tell, they focus on REM sleep and seem to classify non-REM sleep as “wasted” sleep, as if it exists only to propel us from one REM session to the next. Eh, I’m not so sure we should be so flippant about messing with a vital physiological process, nor should we immediately discount the importance of “useless” sleep. I have no problem with hacks, usually. In fact, I usually welcome them. Just be careful when hacking something like sleep.
Okay, so how do I do it?
First, you want to determine what kind of biphasic sleep pattern is even possible for you. If you have the freedom to get to bed shortly after dark, wake up in the middle of the night for a couple hours, and go back to bed, go for natural biphasic sleep.
- Choose an “absolute latest” morning wakeup time. If you have to be up by 7 AM, that’s going to determine how late you can go to bed.
- Determine a bedtime. It should be at least nine hours from bedtime to morning wakeup time, giving you two four hour sleep blocks and one hour of free time in between. If you’re up by 7 AM, you should be in bed by 10 PM. If you want another hour in the middle of the night to do stuff, go to bed by 9 PM.
- Reduce exposure to artificial light once the sun goes down, or at least two hours before your scheduled bed time, just like it would have been for most of human history. Turn off the TV, install f.lux on your computer, light some candles, and/or wear blue light-blocking glasses or goggles. It probably won’t work as well otherwise.
- If you use lighting during your mid-phase waking period, be sure to wear blue light-blocking goggles or stick to a natural light, like candle or yellow light. Try not to bust out the PS3 for some online gaming.
If you need more alert waking time in a day and would like to try reducing the amount of sleep you require, try modified biphasic sleep.
- Choose a 4.5 hour block of time. This will be your “anchor” block of sleep, and most people have success placing this at night or during early morning. Try 10 PM-2:30 AM, perhaps, or 2:00 AM-6:30 AM. Set an alarm, at least until you become entrained to that schedule.
- Wake up and go about your day. Get some light exposure, preferably daylight if applicable.
- Take a 90 minute nap, to begin 8-10 hours after your wake up time. If you woke up at 6:30 AM, you might nap from 4:30 PM-6 PM.
Set a realistic goal:
- “I want to improve my sleep.”
- “I want to feel just as refreshed on less sleep.”
Come up with a hypothesis, like:
- “Modified biphasic sleep will reduce my sleep requirements while maintaining my wakefulness, productivity, workout recovery, and immune function.”
- “Natural biphasic sleep will reduce my nighttime anxiety about waking up and ruining my sleep, thereby improving my sleep.”
Now, we identify some of the variables and think about how they might affect the outcome:
- Length of sleep blocks – Are four hours enough during natural biphasic sleep? Do you prefer two three hour blocks instead of a 4.5 hour block and a 90 minute nap?
- Timing of sleep blocks – Do you need less time in between the anchor block and the nap? How do you sleep with one hour between your two sleep phases? How about two hours?
- Alarm – Does the alarm help or hinder your biphasic sleep?
- Light – How does light exposure affect the effectiveness of your biphasic sleep? Is total abstention before bedtime necessary?
- Activity while awake – What are you using your free awake time to do? Does reading by candlelight have a different effect on sleep quality when compared to going for a walk?
Next, let’s take some measurements. What to measure?
- Productivity - Is your work suffering or improving? How many productive hours are you getting?
- General wakefulness – How are your energy levels throughout the day? Are you getting a mid afternoon slump? Use a simple 1-10 scale.
- Grogginess – Do you feel well-rested upon waking? After which phase do you feel the most rested? 1-10 scale.
- Recovery – How are your workouts? Are your numbers improving or falling?
- Immune system – Are you getting sick more often?
Try the biphasic sleep for at least a week, preferably closer to four weeks. Then once you’ve established a baseline and have some data to work with, refer to the list of variables above, make a change to a single variable, and give it another try for some duration to see if biphasic sleep is for you.
This isn’t for everyone. As Robb Wolf points out, when you have 14 hours of uninterrupted darkness and potential sleep time, you have the luxury of being a little more picky with your sleep patterns. When you don’t have emails to answer or an unprecedented renaissance of quality television to tear into, you’re going to get sleepy when darkness falls, go to bed pretty early, wake up after several hours, do your thing, and go back to sleep for another several hours. Biphasic sleep is probably natural. But we’re not living in very natural times. Or, if we are, natural means something different from what it once did. That’s the whole premise of the Primal Blueprint, after all – identifying what our ancient genes expect from the environment and figuring out how to modify our modern environment to fit those genes.
Let me know what you think in the comment board, and be sure to check out today’s contest.
Grab a copy of Primal Blueprint Quick & Easy Meals for over 100 Primal Recipes You Can Prepare in 30 Minutes or Less
Posted By: Mark Sisson
I have slept with this concept for sometime and I thoroughly enjoy it… That 8 hour crap is for the birds.
Didn’t I read on this site, that this 1-2 hours of semi wakeful time is when your body releases HGH ? What would the effect of actually becoming active Be?
Funny, I was just reading a particular passage in “The Primal Blueprint” book on Grok and family napping by the river in the mid-day.
My sleep doesn’t always have me feeling rested and I often feel like I would benefit from an afternoon nap. I’ll give this a shot!
I usually set my alarm for 7 – 8hrs, but almost always wake up after 5 – 6hrs. I read the news and MDA in bed right after I wake up, and if I’m really tired after my hour or so of reading I’ll sleep about 90mins more.
If I sleep more than 7 1/2 hrs in one phase I usually feel like I have the flu w/o fever and walk around like a zombie all day. If I oversleep in my second phase this also tends to happen. My most energetic days are usually when I’ve slept less than 6hrs.
This really sheds light into ‘siesta’ cultures. I live in one now and could never figure out how everyone was staying up SO late and still waking hours before me… Finally I realized they all sleep in the afternoon! It seemed silly to me at first, but I guess it isn’t so crazy after all!
Good point. I made the comment below that I sleep very heavily during the winter months, requiring lots of hours, and very lightly during the summer months.
There might be a link between biphasic sleep and the phenomena of “siestas” in warm/hot countries with lots of sunlight and heat.
Did the Inuit have biphasic sleeping patterns? It would be interesting to find out.
During the summer months, I tend to go to bed at 11 pm and I’m usually naturally up by 6:30 am (no alarm) cause of the sunlight.
During the long, dark, Canadian winters, I do find myself waking up at 3 or 4 am, being alert for 30 minutes or so and then going back to sleep only to wake up a little groggy at 7 am (while it’s still dark outside).
My desire to sleep, and sleep heavily at that, are strongest in the winter and I think that is why biphasic sleeping didn’t work for me then. The impact of natural sunlight must play a factor in this sort of sleeping pattern.
Regardless, I’ll try out this test now that it’s summer and I feel like I don’t need that much sleep and I’ll see how I feel.
I just thought I had middle of the night insomnia. I prefer it when my wakeful period is less than an hour, preferably less than 10 minutes and that is easier now I’m no longer worried about waking up. If I stay awake longer than I would like I just meditate and usually find I go back to sleep. In winter I like to be in bed by 9pm and up again around 7.00 or 7.30 ie dawn. In summer I go to bed around 10pm and can be up and walking the dog around 5am, and the less sleep doesn’t bother me then.
Just as an aside. I sat in cold water last night before bed (can’t lie in it yet) and had a much deeper sleep than usual last night.
I have always found this type of sleeping pattern to be natural, but whenever I mention it to anyone, they think I’m crazy. In the last couple of years since I started working 12-hour night shifts three times a week, this four-hour-sleep then another sleep of whatever length I need works great at keeping me from being worn out.
Eat when you’re hungry, sleep when you’re tired. Of course real life intervenes, but just like everything else, do the best you can!
(Off-topic)
News Flash! Just in: Paleo diet hits the bigtime: now featured on page 20 of the June 18th issue of the authoritative medical journal “Woman’s World” (available at your grocery store checkout line).
I remember on the farm I often did the biphasic sleep pattern out of necessity, whether it was because of calving season or the irrigation canals needed to be changed, it allowed me to get some sleep and I still felt good; I always chocked it up to the vigour of youth. I cannot see this pattern working in my world now, as much as it makes sense, being a nurse and having shifts around the clock would make this impossible for me and probably most shift workers.
As a breastfeeding mom to a newborn, I find this already a natural part of my sleep pattern. However, I’m up multiple times with sleep in between rather than two blocks of sleep. I was listening to a podcast on Underground Wellness about sleep and the doctor in there mentioned that breastfeeding hormones allow for the mom to get up and down multiple times without getting too sleep deprived. Now I wonder if it has more to do with biphasic sleeping.
Also, interesting to note, in the first month of breastfeeding a womans body produced prolactin to bring in the milk supply. This has the effect of making the mom feel drugged and drift off to sleep while breastfeeding. I’ve caught myself more than once jerking awake while nursing. At least it’s normal.
Islam actually prescribes biphasic sleep by encouraging nighttime prayers, preferably made after some period of sleep, and finishing off with a mandatory dawn prayer. since most people fall back asleep after that, its biphasic
I would really love to try this, as I think I could benefit from it. I don’t know how I can fit it in with my schedule, though. I have to leave for work by 7:45am, and don’t get home until 6:30pm. I figure I could do something like 830pm-1230pm, and 230-630pm… But it doesn’t exactly leave opportunities for spending time with family and friends.
Any suggestions?
I too notice I wake up after 3-4 hours of sleep. I also find it helpful to take about 30 minutes reading and meditating then going back to sleep.
I naturally have this sleep pattern, and have had it on and off for years. Go to bed at 11pm, wake up for an hour around 3am, eventually get back to sleep and wake up again at 8am.
The only good thing about this is that I start work later than most people, so I get in 8 hours. For the rest I never feel fully relaxed or rested. I’ve been paleo for 6 months and that has made no difference to this pattern.
My N=1 experiment feedback – biphasic sleep sucks ass.
I think I’ve done this by accident and felt great. Like when I get up and deal with overseas stuff online. I know jumping on the computer probably isn’t the best thing, but the idea of two phased sleep has worked in my favor in the past. I just didn’t know why.
I switched to a Biphasic Sleep pattern a couple months ago and while I havent stuck to it 100% (I’m in NYC where life DOES happen at all hours) it has definitely changed the way I live.
I used to fall asleep on the couch somewhere around 10pm, sleep poorly then go to bed later, getting between 5 and 7 hours of “bed sleep” afterwards. Now I take a 90 minute nap somewhere around 8 or 8:30, wake up refreshed an ready to go then get 3 more hours usually between 2 and 5 or 3 and 6 depending when I want to get up.
This not only reduces the number of hours spent on sleep to 4.5 (sounds ridiculous right?) but I feel better rested all day, avoid my mid-afternoon slump (even without coffee) and ALL the time I am awake is more productive. I use my “Bonus Time” between sleeps for walking the dogs, housework, listening to coast2coast AM (guilty pleasure but its on from 1-4am for me so I rarely got to enjoy it otherwise), getting ahead on work for the next day or just reading and taking a break.
Being able to skip a day or to drop it for a few days if necessary certainly makes it easier to adjust. If there is something going on, I just sleep in one block in multiples of the 90 minute cycle (6, 7.5 etc). If I am more tired than usual, I will extend one of the sleep periods by a cycle (3 and 3, 1.5 and 4.5 etc). I feel like it gives me the tools to get the optimal amount of sleep. Not too much, not too little.
As far as Mark’s Metrics (I’m a Web Analytics consultant, data is a passion):
Productivity – I am FAR more productive, especially given the additional time I can devote to work if necessary.
General wakefulness – 9-10, depending on the time of day
Grogginess – I actually feel more rested after my first (shorter) phase. at that point I wake up around 8-9 then level off higher.
Recovery – Workouts are noticeably better when following biphasic sleep.
Immune system – I am getting sick less often and my Seasonal Allergies are less severe
I was a but surprised to see the sweeping generalizations in an earlier post (the MDA community is usually just so nice!). From a later response, it looks like the comments about programmers were tongue in cheek(?) but the lifehacker bit in the comments is ridiculous. Isn’t Paleo/Primal the biggest lifehack of all? Lifehacking is all about solving a problem in a non-standard way and even though Paleo/Primal living focuses on trying to mimic the way our ancestors did things, in today’s society it is far from “normal”.
As with anything else (Paleo/Primal included) don’t knock it ’til you try it because you just may like it!
Mark – Great post! It cant have been more than 2 weeks since I searched the site for your take on Biphasic Sleep and I’m glad to see your interest (even if cautious) and hear your take on the subject.
I’m the one who slammed ‘Lifehackers’, so I guess I will respond. I admit I was using the term as it originally meant (a definite misnomer, if you ask me), i.e., little tricks busy software people use to speed up their workflow and ‘productivity’ (a term I detest).
Mark and others use the term in its more recent meaning, apparently, having to do with tweaking parts of your lifestyle for personal betterment. I’m all for that. Sign me up. But I kinda reject the characterization of Primal or Paleo as a lifehack. It’s bigger than that, more of a paradigm shift. The Squatty Potty is a lifehack.
Sometimes one has to turn things upside down to make things better, rather than tweaking one’s life to patterns that others have set. E.g., if your boss wants you to go on a rotating shift (a recipe for ill-health in many people), you might try to accomodate this by various lifehacks, but you would probably be better off getting a new job less dangerous to your health.
I have been doing a modified version of this quite accidentally for about a year now. My body is quite happy on 10 hours of sleep, but with my 5AM wake up call, that would mean a 7PM bed time, and no time at all with my husband or family!
I go to bed absolutely no later than 10 and get up at 5 to make breakfast, do morning chores and get the kids to their respective jobs. At about 10 in the morning, I settle in for a 90-minute nap. I wake up and make lunch and finish up the day without needing an afternoon “jolt” like I used to.
I wondered if I was harming myself by not sleeping in one big chunk, or maybe messing with my calorie burn by napping. But, it works for me and my 8.5 hour biphasic sleep is as restful as a 10 hour chunk.
I was able to do this for a few months several years ago and loved it! I had a part-time job that ended at 2 pm, so I’d come home and nap for a couple of hours. Then I’d get up and work on the arts I sold on the weekends at craft fairs until 1 or 2 am. It was a great way to get the right amount of rest, plus I have always been more creative late at night. It turned out to be the best of both worlds for me.
How interesting. This happened to me last night. I’m dog sitting and one of them woke me up to go outside but then I couldn’t get back to bed. I was up for about 2 hours, spent the time worrying about getting back to sleep and getting enough and then got up about 3 hours later. I feel fine…
Biphasic sleep sounds very interesting, I think I’ll give it a try.
I like this concept, I have been napping everyday for awhile now and love it. I’ve been in a bad habit lately of going to bed around midnight because I’ve been watching the playoffs but when I used to go to bed around 9:30 p.m. I would naturally wake up around 4:00 a.m with tons of energy. I’d get up and maybe read a little and go back to sleep around 5:30 and sleep til 7:30 and I felt so refreshed doing this.
This is amazing–so glad I read it. For the last 10 months, I have been dropping to sleep at 9:30 or 10; sleeping till 1 or 2, then awake till 3, and sleeping till 6:30. I thought something was wrong with me, yet I felt fine.I have had a higher level of stress, yet this has seemed to work. I wonder if people eating an American diet have this pattern, or it may also be to our paleolithic lifestyle just lends itself to this…………?
I always wake up around 2:30 am. Every night. Get up to pee, lay back down. The mind is active. I meditate/pray for about 20 minutes and fall back to sleep to wake up with the birds and sunshine. I am glad this is normal and has a name! I thought I had just created a habit.(or had a small bladder..)
Husband does the same and will often get up and do things for awhile. He did think it was a sleep problem. I can’t wait to read this article to him! As always, very informative. Thank you!
My thoughts exactly, since going primal everything has changed for me.
I get very tired around 6pm some nights, and could easily go to sleep.
What would happen is I would wake around midnight, I’d get up, be lucid and alert and really motivated to do stuff.
I felt guilty and stupid doing “stuff” in the night, and would force myself to GO TO BED.
I would then sleep until about 9am if I wasn’t woken by my alarm at 7am.
I am a sleepy head. I can function on 6hrs but only if it’s a once in a blue moon event. I usually get about 8hrs and feel tired. If I get 9-10 hours I feel like I could do anything…
Breaking it into two blocks might reduce my sleep hours but leave me feeling refreshed?
Something to consider…
Jane
One of the most important variables determining how people sleep is the latitude where they live. People (and animals), generally at or above 45 degrees latitude, are greatly influenced by seasonable changes in daylight hours. At 50 degrees this time of year (of maximal daylight hours) naturally induces a long midday nap and less sleep at night. But in the winter around the end of December much longer sleep is required at night and a short midday nap . This is naturally the case with those people in tune with their environment at these latitudes – those who work outdoors, or spend most of their time outdoors.
I also began waking after that first four hours, falling asleep and waking again 4 hours later. At first I was annoyed but when it didn’t affect my energy negatively for the day I just started going with it.
There’s a great documentary on Netflix by Nova on dreams that I watched about a year ago. They did sleep experiments and found that we dream in both REM and non REM sleep and they are different types of dreams and equally important. Anybody interested in the lifehack option should watch it and then decide. If the lifehack completely eliminates time in nonREM, there may be unforeseen consequences.
How is this going to work for those of us in the northern reaches? I’m only in Germany, and it is fully light at 4:30a.m. and sun goes down around 9:30p.m. That’s not enough time for your experiment, during the summer – plenty of opportunity in the winter, of course!
This explains so much! I have always fallen asleep soundly for a brief period only to be fully awake in a short time. This can range anywhere from 15 minutes to 1-1/2 hours. I think the 15 minute variety is just leftover from my college days of dozing in the classroom.
This “insomnia” is most prevalent in the summertime and the mention of shorter days made sense. In the winter, I don’t sleep like that at all.
I talked to my physician about it and he was baffled because he thought if it were a seasonal disorder I would have trouble in the winter and offered pills, which I declined.
This sleep pattern also runs in my family as my mother and grandmother had/have it as well.
Now if I could only convince my wife she should wake up with me.
I have a question for Mark, or anyone else that knows, regarding the modified biphasic schedule.
I work 10 hour shifts and travel about 30 minutes each way to/from work. That gives rougly 11 hours between when I walk out the door and back in, which means about 11.5 hours from when I wake up to when I get home.
Is it a hard and fast rule that you must be taking your 90 minute nap within 10 hours of initially waking up or can I adapt this plan to be a 90 minute nap 12 hours after my anchor sleep?