Marks Daily Apple
Serving up health and fitness insights (daily, of course) with a side of irreverence.
5 Jan

Dear Mark: Seasonal Affective Disorder and Light Box Therapy

With holiday fun come and gone, it’s the time of year when we all truly settle into winter. Spring is a long way off at this point. The cold and darkness aren’t going anywhere any time soon. Most people find their way through the season with a mixture of enjoyment and impatience (and maybe a warm weather vacay), but others have serious reason to dread it each year. Few of us, I think, like giving up our extra hours of daylight. The relative darkness of winter, however, presents a particularly harsh challenge to those who battle SAD – Seasonal Affective Disorder – a form of depression associated with fall and winter’s more limited sunlight.

Dear Mark,

I’m curious if you’ve done any research into the viability of full spectrum light lamps in combating SAD. I can’t get outside much during the limited daylight hours this winter and I’m noticing a marked dive in my mood – I was diagnosed as clinically depressed in college and while I’ve been able to combat it mostly through living Primally, I’m finding it especially difficult this winter (again, probably due to the fact that I really can’t go out during the day right now.) So have you done any research or know of any studies stating how harmful or beneficial these lights are, especially regarding UV rays? Thank you!


Experts believe that reduced sunlight in fall and winter throws a wrench in SAD sufferers’ circadian rhythms and disrupts their bodies’ hormonal regulation, lowering serotonin levels and/or increasing melatonin for example. Those with SAD (not to be confused with the Standard American Diet) see their everyday lives upset by symptoms such as depression, fatigue, sleepiness, irritability, and concentration difficulties. The hallmark indication of SAD is timing of course: symptoms generally begin in the fall, peak in winter, and decline in spring as daylight hours increase.

Estimates vary but suggest between 4 and 6 percent of people in the U.S. have SAD. (An additional 10-20% of us experience a less serious form of “winter blues.”) Not surprisingly, folks farther north are more at risk than those of us who live closer to the equator. Women (particularly those in their 20s-40s) appear to develop SAD more often than men, but experts don’t know why at this time.

The most common form of treatment is, as Katie suggests, phototherapy. People with SAD are generally prescribed daily use of a light box that emits bright, full spectrum light intended to mimic natural daylight. Experts usually recommend doing the daily session as soon as possible after waking up. Important features of effective light therapy include blue light exposure and total intensity (lux) power. Light boxes/lamps should be 10,000 lux (much more intense than your average home light bulb) and should include blue light for full effectiveness (PDF).

Before buying one, make sure the model you’ve chosen is specifically for SAD therapy and uses blue and not white light. Also, the model should fit the 10,000 lux recommendation – within 1-2 feet distance from the device. (Having it right next to your face for half an hour each day will get old fast.) Expect to pay anywhere from $100-500.

Light boxes do present some risks. (Doesn’t everything in life come with a “but” at some point?) Some users report eye strain and/or headache following the initial sessions, but these effects generally subside. Less common (but still generally minor) side effects include nausea, agitation, and sleep difficulties. Ultraviolet light risks, as Katie mentions, aren’t a concern for light box users because these devices are purposely designed to filter out UV rays. (UV rays are used in other light therapy uses, such as phototherapy for certain skin disorders, which is why it’s essential your model is designed for SAD.)

In recent years, however, experts have warned of risks associated with prolonged exposure to blue light. Over time, blue light can potentially cause retinal damage and macular degeneration. Because blue light appears to be an important component of light therapy for many people with SAD, redirecting the light box or using glasses that filter it might decrease the therapy’s impact. (Kind of a Catch-22, isn’t it?) Research is beginning to look at other, potentially safer options, including the use of green light.

Right now there’s no overwhelming consensus or dramatic concern for this risk. Although the light needs to be directed toward your eyes, don’t look directly at the light box. Obviously, use your light box for the prescribed time each day (and no more), and talk to your doctor before increasing your exposure time. It’s probably a good idea to see an ophthalmologist each year to assess any early warning signs for eye damage. If you’re on a medication that makes your eyes more sensitive to light, it’s especially important to talk to your doctor before beginning light therapy.

Other risks involving light boxes relate to their overuse, which can swing the neurotransmitter pendulum in the opposite direction. Excessive exposure to light boxes can result in ongoing insomnia (especially if used late in the day) or – in some cases – mania. Although a half an hour a day might be the general recommendation, the optimum treatment time will be individual.

It’s important to know that phototherapy doesn’t fully turn around depression and associated symptoms in every person diagnosed with SAD. Those who’ve been diagnosed with SAD can take advantage of other therapeutic options. Vitamin D supplementation becomes a key treatment in some folks, particularly because vitamin D levels are closely tied to direct sun exposure. Research has also shown regular exercise to be an effective therapy for every form of depression. As for conventional anti-depressants, it’s true some people with SAD find relief with them, but the side effects for these medications present their own difficulties that must be measured against their potential benefits. There are alternative depression supplements like St. John’s Wort and – an always healthy option – fish oil. (I’d suggest getting thyroid levels checked as well, since thyroid function can fluctuate from season to season.)

Finally, a study from the University of Vermont showed that cognitive behavior therapy for SAD resulted in a lower SAD recurrence rate (5.5%) the following year than either light therapy (36.7%) or combination light therapy-cognitive behavior therapy (7%). (The combination therapy, however, was significantly more effective at inducing remission of SAD [80%] than either cognitive-behavior therapy or light therapy alone [both 50%].)

For the rest of us who might wonder if we fit the “winter blues” category or who are just feeling impatient already for longer, brighter days, the same core principles hold. Get outside as much and as early as possible. When indoors, expose yourself to as much light as you can during the morning and afternoon, but curtail light in the hours before bed. Invest in some full spectrum light bulbs, which won’t offer the boost of a therapeutic light box but can offer a better option than plain incandescent bulbs. Arm your well-being with plenty of physical activity, a good Primal diet, and some wisely supplemented vitamin D and fish oil, which are both used to prevent and treat forms of depression. Find a way to enjoy the season each day, and rest assured that spring will eventually come!

Have thoughts for Katie or suggestions for light box therapy? Thanks for reading today, and be sure to share your feedback.

You want comments? We got comments:

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  1. Since moving from South Africa to the UK I’ve found myself becoming virtually non-functional from November until late April/early May.

    I use a Britebox SAD light which does help a bit, but I’m hoping to see a big difference this year since going primal in August.

    One thing I was told is to never use St John’s Wort in conjunction with light box therapy as that can increase the risk of retinal damage.

    Karen vW wrote on November 26th, 2011
  2. I have SAD , except my despression worsens at night , every night .

    Rachel wrote on May 19th, 2012
    • Oh me too. I have to take anxiety medicine most nights because I get panicky when the sun sets. I’m *not* looking forward to the impending time change. I’m hoping some light therapy works.

      Hilary wrote on October 2nd, 2012
  3. I know this is an old post, but I wanted to add my 2 cents anyway. I’ve had seasonal changes in my mood and energy for as long as I can remember and have been diagnosed with SAD, but I’m not sure that it is a pathology. I think it is a natural, primal adaptation to help us survive the long, dark winters in northern climates where you need to spend long dark hours in sheltered locations. Think how bad your cabin fever would be if you didn’t have a reduced energy level and didn’t want to sleep most of the night and day away. I haven’t seen much on human hibernation or semi-hibernation, but this page talk about it, as well as Wikipedia’s page on SAD, , and Charles Frasier’s book 13 Moons describes it in the Cherokee tradition. I only feel irritable and depressed in winter when I am tasked with doing more in my day than I have the energy for. Conversely, in summer when the days are long I think I have above average energy. I think it is the frenetic pace of modern life that makes us suffer from SAD, rather than benefit from it. As a modern human, I boost my energy level in fall and winter with trips to sunny climates, Vit D intake, and outdoor winter sports. I love skiing b/c it is exhilarating, gets me outdoors for a full day and gives me a reason to look forward to winter. When we have late fall and winter rain and grey in western Washington where I live, it is usually snowing in the mountains!

    Kristina wrote on November 20th, 2013

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