Will a Light Box Actually Help My Winter Depression?

Light Therapy, Part 2. Part 1 covers light therapy more broadly, including depression that isn’t seasonal. This part covers the protocol for seasonal depression and what changes if you have bipolar disorder.

“Every year it’s the same. By November I’m sleeping ten hours, eating everything, and still dragging. Does a light box actually do anything?”

For seasonal affective disorder, yes. Light therapy is one of the best-supported treatments we have for winter depression, and in the one large trial that put it head to head with an antidepressant, it did about as well. The catch is that it only works at the right dose and the right time of day, and a lot of what gets sold as a light box can’t deliver that dose. It’s one of the non-pharmacological recommendations I make every winter, and I follow it myself.

Is it seasonal depression or just winter?

Most people feel slower when the days get short. Seasonal affective disorder is a depressive episode that keeps a calendar; mood drops in fall or winter and lifts in spring or summer, year after year. Light tends to help most when that winter picture includes oversleeping and overeating.

I’d confirm that pattern with a clinician before buying anything. A nonseasonal depression that happens to start in October, or bipolar disorder, can look like “winter blues” at first, and bipolar disorder changes how light should be used.

What the evidence for light therapy in SAD shows

Light therapy has been tested in more than 100 clinical trials since the early 1980s, and The Carlat Psychiatry Report puts its effect size for winter depression at 0.5 to 0.8, which compares well with medication. Light also helps some depression that isn’t seasonal, which I covered in Part 1; this post sticks to the winter pattern.

The trial I point patients to is Can-SAD. Ninety-six people with winter depression got eight weeks of either a 10,000 lux light box for 30 minutes each morning plus a placebo pill, or fluoxetine (Prozac) 20 mg plus a dim placebo light. About two-thirds of each group responded, and remission rates were close (50% with light, 54% with fluoxetine). Light pulled ahead at week one, and fluoxetine caused more agitation, sleep disturbance, and palpitations. The limit is that there was no group with both a placebo pill and a placebo light, so the study shows the two were comparable, not how far either beat doing nothing.

One detail from that research matters at home. The dim light used as a placebo in trials is about as bright as an ordinary room; indoor light runs roughly 300 to 1,000 lux. A sunny window seat or a bright desk lamp can feel nice, but it isn’t the treatment.

How to use a light box for SAD

The dose is white light at 10,000 lux at your eyes. Below about 3,000 lux it doesn’t work.

Use it soon after you wake up, at the same time every day. For most people that lands somewhere between 5 and 8 am; earlier for morning people, later for night owls. Don’t use it late in the day. The Carlat sources put the cutoff at 2 pm in one place and 2:30 pm in another, so I tell people to finish by early afternoon; later light can push your body clock the wrong way and disturb sleep.

Start with 30 minutes. Most people end up needing 30 to 60. Some notice a change within a few days; most should be clearly better by about two weeks. If nothing has moved by days 10 to 14, going up to 60 minutes is reasonable.

The box should sit slightly above eye level and angle down toward you, roughly 30 to 45 degrees. Eyes open, but don’t stare into it; reading, eating, or working on a laptop is fine. Regular glasses are okay. Sunglasses, tinted, transition, or blue-blocking lenses defeat the purpose. For distance, follow your box’s rating. Most full-size boxes are rated at about 12 to 14 inches, some farther out, and even the Carlat sources differ on this.

If your pattern is predictable, start about two weeks before your usual low, keep going through winter, and taper over about two weeks in spring. Missing a day or two is usually fine. Missed mornings, week after week, are the usual reason it “didn’t work,” far more often than the box itself.

If you have bipolar disorder

Winter depression is common in bipolar disorder, and so is the opposite problem in spring, when the jump in daylight can tip some people into mania or a mixed state. A light box can do the same thing if it’s ramped up too fast or used first thing in the morning. So talk to your clinician before starting, and expect a different protocol.

The one I use is midday light, between noon and 2 pm, starting at 15 minutes a day and adding 15 minutes each week toward an hour. Some trials have used morning light in bipolar depression without triggering mania, but I stick with midday for bipolar I, or for anyone who has had manic or mixed symptoms in the past six months.

The evidence is encouraging and still thin. In a small pilot trial, people with bipolar depression who stayed on their usual medications and added 30 minutes of daily bright light had lower depression scores at eight weeks, though not yet at four. In bipolar depression, I treat light as an add-on to mood stabilizers, not a replacement for them.

If you feel irritable, unusually “up,” restless, or find you need less sleep, stop the light and call your clinician. Restarting usually means less time, sitting a bit farther back, or moving the session to midday.

Eyes, medications, and side effects

If you have glaucoma, cataracts, macular degeneration, or retinal disease (including diabetic eye disease), see your eye doctor first. Be careful if you take photosensitizing medications such as lamotrigine, tricyclic antidepressants, or antipsychotics, or if you have lupus. Use a box with a UV filter. Never use a sunlamp or a tanning lamp.

The common side effects are headache, eye strain, and mild nausea, usually early and usually better with a shorter session or sitting a bit farther back.

You can keep taking your psychiatric medications; light can be added to an antidepressant rather than replacing it. It isn’t a reason to skip an evaluation. If you’re having thoughts of suicide, call or text 988 (in the US), or go to the nearest emergency room.

The light box I use, and the one I’d start with

I use the Alaska Northern Lights Aurora LightPad Mini, mostly because it’s portable and comes with me. To be fair about it, its face is small: about 7.5 by 5.25 inches, roughly 40 square inches. The Center for Environmental Therapeutics recommends a screen over 200 square inches, and the Carlat protocol asks for at least 12 by 15 inches. The maker rates it at 10,000 lux at 25 inches, but with a small face, small head movements can drop the dose you actually get. It fits my routine; it isn’t the standard pick.

If you’re buying one box for seasonal depression, the Carex Day-Light Classic Plus is the full-size choice I’d start with. It’s rated at 10,000 lux at 12 to 14 inches, has a screen of about 16 by 13 inches (around 208 square inches), filters UV, and is one of the brands Carlat names as reliable. Prices change often, so I’m not listing them.

Be skeptical of the cheapest lamps on big marketplaces; some only reach 10,000 lux a few inches from your face. CET’s guide to choosing a light box lays out the criteria.

None of the product links I share here, in this post or anywhere else on this site, are affiliate links. I don’t earn anything if you buy either box.

This is general information, not personalized medical advice. Don’t start, stop, or change a treatment without talking to your own clinician, especially if you have bipolar disorder, eye disease, or take photosensitizing medications.

This article was written in my own words with the help of Wispr Flow, a voice-to-text tool I use for drafting. Try Wispr Flow here. This is a referral link, and I may receive account credit if you sign up through it.

References

1. Lam RW, Levitt AJ, Levitan RD, et al. The Can-SAD study: a randomized controlled trial of the effectiveness of light therapy and fluoxetine in patients with winter seasonal affective disorder. American Journal of Psychiatry. 2006;163(5):805-812. doi:10.1176/ajp.2006.163.5.805. PubMed
2. Aiken C. A practical guide to light therapy. The Carlat Psychiatry Report. November 15, 2019. Link
3. Higgins EM. Pocket protocol for light therapy (reference table). The Carlat Psychiatry Report. 2021;19(10). PDF
4. Bright light therapy fact sheet. Medication Fact Book for Psychiatric Practice, 7th ed. Carlat Publishing. PDF
5. UBC Mood Disorders Centre. Procedure for using the 10,000 lux fluorescent light box. University of British Columbia. Link
6. Cuomo A, Carmellini P, Garo ML, et al. Effectiveness of light therapy as adjunctive treatment in bipolar depression: a pilot study. Journal of Affective Disorders. 2023;321:102-107. doi:10.1016/j.jad.2022.10.009. PubMed
7. Center for Environmental Therapeutics. How to select a light box. Link