Light Therapies For Depression

Table of Contents

Warning: Don’t do this on your own. There are risks, described below. But these risks are almost certainly much smaller than those of medication approaches.

Bottom line:  clearly more than a placebo. Dawn simulators are the first step (much easier to use, cheaper, no risk). If you are going to use a light box, read on.

How much light are you getting?

Light therapy can treat more than just winter depression, though that’s the main use. Here’s why: the amount of light reaching your eyeball from interior lighting is far less than the amount from the real thing. So unless you are outside much of the day in the winter, you are relying on electric light for your photons (in summer, there is so much light, most people get enough, even if they are indoors during their work hours). The following graph shows you just how much less light you receive, indoors versus outdoors (Lux is a standard unit of light flow):

Brightness Values:

Candle light at 20 cm 10-15 Lux
Street light 10-20 Lux
Normal living room lighting 100 Lux
Office fluorescent light 300-500 Lux
Halogen lamp 750 Lux
Sunlight, 1 hour before sunset 1000 Lux
Daylight, cloudy sky 5000 Lux
Daylight, clear sky 10,000 Lux
Bright sunlight > 20,000 Lux

So an outdoor summer day is 50 times brighter than your average indoor room. Okay, with that as an introduction, let’s look at light as a treatment for depression.

Start with a dawn simulator

Hold on a minute, before you go tearing off looking at light boxes (discussed below) . . . There is a far simpler way to do light therapy, which is even cheaper and so far has not been associated with hypomania or mania (which light boxes can cause).   It doesn’t work for everyone. But “treatment” is over by the time you wake up. No sitting for 30 minutes stuck in front of a light box.   If it doesn’t work, you might still like it (wouldn’t you rather wake up in room full of light than wake to an alarm and have to — whamo — turn on a bright light? ugh).

What is a “Dawn Simulator”? This is simply a device to gradually increase the light in your bedroom in the morning, while you are still asleep. Try this: close your eyes and look toward the light by which you’re reading this. You can tell where the light is, even with your eyes closed. A dawn simulator gradually turns on your bedside lamp in the morning, before you wake up, so that your retina (not you — you’re still asleep!) “sees” the light show up at the time you choose, increasing gradually just as natural sunlight does, over about 30-45 minutes. It’s really nothing more than a timer and a rheostat (a device to slowly change electrical current) hooked to your bedside lamp. Note that this approach does not require a “light box”.

Why is the gradual appearance of morning light potentially “antidepressant”? Think of it this way: the dawn simulator is trying to convince your brain that it’s still July out there (even in December). It turns out that your brain knows what season it is primarily by the time at which morning light appears (okay, it’s true, you can also tell the difference between snow, sleet, ice, freezing rain, and the warm summer sun; but evolutionarily, it looks like the brain’s timing was set by factors more closely associated with light.) We think that some people are built to slow down in the winter, something akin to hibernation. Think of a hibernating bear: sleepy, slow, hungry for carbohydrates, unhappy if awakened, grouchy, grrrh. Those symptoms are pretty close to the experience of “winter blues” for some people.

So, if those peoples’ brain could be tricked into thinking that it really isn’t winter after all, might that prevent this shift toward a kind of half-hibernating way of dealing with the world? It appears that for some people, this actually works.

In the following graph, the “negative ion generator” was low-dose, the placebo. (High-dose appears to be an antidepressant of sortsFlory). Notice how the dawn simulator, while not as good as light box, is better than a placebo.Terman (down is getting better, these are depression scores over time from left to right)

DawnSimTrialSo, to review:

  • it’s cheaper
  • it’s over by the time you wake up
  • you might like it even if it doesn’t work for mood
  • it doesn’t make bipolar disorder worse
  • it has no risks (except waking your partner)

Sold?  This page has a few good dawn simulators and more detail on how to use them.

Now, on to light boxes — another way to do light therapy.

Light Boxes: Safety issues

A group of  experts maintains a website ( about all aspects of light therapy. Their discussion of safety issues is thorough; and maybe a little technical, so I’ll summarize here, but if you have any further need for information, that’s the place to go.

You need to learn more about light box safety before using one if (look up your medications or ask your pharmacist; ask your eye doc’;  or at least read the site’s page about risk):

  • You have macular degeneration, or a family history of macular degeneration
  • You have porphyria, lupus, actinic dermatitis (seriously sun-damaged skin), or solar urticaria (sun makes your skin hurt)
  • You take a medication that sensitizes you to light (some antipsychotics called phenothiazines, tricyclic antidepressants, St John’s Wort, tetracycline, antimalarials, diuretics like hydrochlorathiazide, sulfa antibiotics, and some medications for rheumatoid arthritis, cardiac arrhythmias, and psoriasis.
  • And if you have diabetes and eye problems from that — well, you get the drift. This is high intensity light. You have to be careful with it.

Light Works Differently in Bipolar Disorder

If you already have figured out you have some degree of bipolarity (Bipolar II, soft bipolar disorder), then before you read on you should probably read about Bipolar Disorder: Light and Darkness.  Because there’s more to the story than light. Darkness might be even more important, especially if you’re having mixed state depression, because more light might be a bad idea at that point (it’s an antidepressant; antidepressants can induce manic-side symptoms; mixed states are combinations of depressive and manic-side symptoms; so light can induce mixed states, and make them worse. That was the short version).

If you don’t have bipolarity, you can skip to the next section. Mind you, it is not easy to be certain about this. If you have any doubt, read more about bipolar II and more subtle forms of “bipolarity.”  You definitely should do this if you have someone in your family with a bipolar diagnosis.

Light Therapy in Bipolar Disorder

Light therapy is one of the safer antidepressant treatments for bipolar depression, and it’s pretty potent as well. Starting in 2018 the controlled studies started to roll out, and the results they found are about as good as what we see with antidepressants.

Those studies also brought some reassurance on the manic question.Sit, Zhou Compared to placebo, light therapy didn’t seem to cause any switches into mania or mixed states. But that doesn’t mean we’re fully out of the woods. There are definitely patients who have that reaction, but we can at least say it’s not very common.

One study used an extra-safe design that’s worth considering if you have bipolar disorder.Sit In fact, if you have bipolar I or recent manic symptoms, the safer approach is the way to go. Here’s what you do:

  1. Start slowly, with just 15 minutes per day and increase by 15 minutes per week toward a “full dose” of one hour (you’ll get there in 4 weeks). If you develop manic symptoms, contact your doctor as you may need to stop it or lower the dose.
  2. Use the light in the early afternoon, between 11:00 am and 2:30 pm. Afternoon light is less destabilizing because your brain is already exposed to a decent amount of light in the afternoon (otherwise, most protocals recommend morning light).Liebenluft

Light boxes are better than placebos

How about a head-to-head competition between light therapy and a typical antidepressant; wouldn’t that be one of the better ways to demonstrate that light really works to treat depression? Just such a study was  done using 100 patients in Canada, with depression in the winter, randomly assigned to either fluoxetine/Prozac or a standard light box.Lam

Here’s what happened — equal improvement in both groups, with light a slight bit faster in lowering depression scores (lower is better) at week one; fluoxetine in red, light therapy in blue; improvement is shown as a reduction in depression scores:

How about that? Light therapy was as good as the standard antidepressant approach. With fewer side effects and much less overall risk (not zero risk, but less).

If you’re not familiar with light therapy for seasonal depression, more information follows below. Basically one sits in front of a box the size of a small suitcase (smaller ones available; more on that below too) which emits a lot of light, for about 30 minutes to start, and as little as 15 minutes or less later to stay well through the winter.

The Canadian research is one of the most recent of several well-designed studies which when viewed together suggest that light therapy is an effective treatment for depression, roughly equal to medications in strength.Golden

So, if light therapy is that good, why isn’t it more widely recommended? For one thing, early research on light therapy was poorly funded and thus often of very weak design. Placebo comparison (“control” treatment) is hard to do. Think about it: how do you put someone on a “placebo” treatment that seems like light therapy but isn’t likely to do anything? It’s not like making an identical placebo pill. Researchers have used dim red light, mis-timed white light, and negative ion generator boxes as “plausible” placebo treatments. All of these control treatments have their problems.

Furthermore, as one of the leading researchers pointed out, everyone in the study is likely to get some additional light exposure just from seeing the sun once in a while. In Seattle, where Dr. Avery works, that might really be once in long while, in the winter! But if all patients in a research study are getting some sunlight during the day, at random times during the study, that ought to minimize the difference between the “treatment” group that is getting light box treatment, versus the “control” group that is getting something else. As Dr. Avery says, it’s as though you were trying to research on Prozac, with one group on the drug and one group getting placebo, but unknown to you, now and then someone was sneaking in and putting little doses of Prozac in the water supply of everyone in the study!

Because of these design problems, and the lack of a major industry to fund research on light treatments, early studies tended to be weak and contributed to the sense that light therapy itself is a weak treatment. And yet the two reports above (one a new study, one a good recent review of previous research) show that light therapy for seasonal mood shifts is not a weak treatment at all. And it may have similar strength even for non-seasonal depression. One study even found that hospital stays for depression were three days shorter for patients whose rooms faced east (thus getting regular morning sunlight), instead of west.Benedetti

Best of all, it is relatively cheap: the newest light boxes cost as little as $80-130 (a link in a moment). Compare the price of medications for a year, plus doctor visits to manage those medications. There are no medication interactions; and there are almost no side effects. Some people get headaches, some have some eye strain. But the main worry with light therapy is that it will work too much like a regular antidepressant: as with other effective antidepressant treatments, there are numerous reports of hypomania developing during light treatment. One of my patients got a speeding ticket after sitting in front of her box too long — twice!

Because of this risk, which includes maniaChan and even suicideHaffmans, you should not attempt light treatment on your own. This must be conducted with your physician as part of the treatment team, which includes planning for managing worsening during treatment. Do not do this on your own

How to Use Light Therapy

There’s a lot to know about light therapy, but here are the basics:

  1. The box should hang over your head like the sun (e.g. at a 45 degree angle).
  2. You need to be close to the box to get the effect (most boxes recommended within 14 inches)
  3. Morning light works better, but people with bipolar disorder may need to use it in the early afternoon.
  4. Avoid using the light after 2:30 pm unless instruted to do so by your physician – there’s a risk it could flip your circadian rhythm (and your mood) the wrong way with that.
  5. Duration matters. The best results are usually with 1 hour of exposure, though some may feel better with 15-30 minutes and others may need 2 hours.
  6. Change the bulbs every 1-3 years – they will still look like they work but overtime they lose some of their therapeutic edge.

Which Light Box Should I Buy?

Basically, you need a big ugly box. The pretty ones that look like they came off a Star Trek set are usually not big enough to work. The DayLight has been recommended for years by and was tested in clinical studies. It’s low-cost, and it’s not that ugly.

A. DayLight: The official research rig

DayLight Classic (folding stand)

DayLight Classic Plus (solid stand)

These two have all the right specs and were tested in clinical research. They have the same light and differ only in the stand (one is folding, one is solid). And, they are relatively low-cost (the price fluctuates a lot, generally $80-120)

Notice that the light box which comes with this stand is higher than her eyeball, and it’s LARGE, so if she moves her head a little the amount of light she sees will not change too much. That’s the crucial difference, comparing the next option.

What About Blue Light Boxes?

As you may have read, blue light is wavelength that sets biological rhythms, including sleep/wake cycles in humans (here’s the whole story). So back around 2005, some companies started making little blue light boxes. They could be smaller because they were emitting just the “active ingredient” in white light. But now there is controversy as to whether blue light boxes, or little light boxes, are as effective as large white ones.

If you want to be really sure you have the same box that most of the research studies have used, you need the LARGE WHITE one above.

Mind you, there is a research study showing that a little blue box is better than a placebo.Glickman But that particular blue light box now costs $150, more than the research-grade box, and with it you get tangled up in both debates: Are blue boxes as good as white? Are little ones as good as big ones?

Finally, yet one more debate gets hauled up about the blue boxes: Maybe they aren’t as safe as white ones — even though at least some of the white ones put out even more high-energy light (higher than blue) than the blue boxes.  All of these boxes have to be evaluated carefully for safety.

What About a Light Visor?

If you have $200 to drop, not just $50, you might consider a green light visor, but only if you have to be walking around at the time you need the light therapy. If you can be sitting down at the needed time, the expense is not worth it, and the data supporting it not substantial enough (yet, anyway; as of 2013). You can’t easily read or use a computer, though it’s not impossible (my experience; versus an aviation study that panned the visor approach). You definitely cannot drive with this rig on.

Does the visor approach really work? The manufacturer offers four studies showing effectiveness versus control treatments. Unfortunately, none of the these has been published, near as I can tell (Pub Med, 11/2014). That should be a red flag. Yet green light has been shown effective in other published work, using a light tower — much more expensive, not portable — instead of a light visor. So even though several large studies with white-light visors did not show benefit versus control treatment (Teicher; Rosenthal), we now know the active ingredient in all that light (blue or blue green; here is the whole story about blue light). So theoretically the green visor might work, even if it does not have published evidence. Therefore you might consider it if you can’t sit for light therapy (e.g. busy parent in the morning?). You look kinda funny with this visor on your head, though: I got quite a few laughs wearing it around the hospital. So this may be a privacy-of-your-own-home thing.

I have to put the light box above my eyes?

Yes. The same team that developed the first blue light box also did an interesting experiment. They put a special helmet on patients undergoing light therapy, which allowed the light to hit only the top of their eyeballs, or the bottom. Why they thought this might be important, I don’t know — but they were right. It turns out you need use a light box positioned above your eyes, so that the light hits the bottom of your retina. Patients in the group with light hitting only the top of their retina did not respond as well to the light therapy.Glickman

Huh? Actually, think about it, this makes a lot of sense. Why would your body bother putting receptors for light at the top of your eyeball? The light you’re interested in is coming from the sky, not the ground, right? Evolutionarily they’d be much more useful at the bottom of the eye; why waste them at the top where they can’t “see” the light they’re supposed to be telling the brain about?

The point here: don’t put that light box on the tabletop next to your bowl of cereal and your newspaper. Put it up on something so that the light is coming down toward you (not very far away though: one foot for the research rig, and 6 inches for the little white box). I’ve been telling my patients for years to put their big suitcase-size light boxes on the table. Wrong.

What Time Should I Use It?

Light can be used for several purposes, including winter depression, which is one version of seasonal affective disorder — SAD, what an acronym. It can also be used for moving your sleep timing, even if you don’t have depression. Here we’ll focus on SAD.

For winter depressions, research has so far focused on using light therapy in the morning. Most studies have shown this to be more effective than evening light, when one timing is compared against the other and no further information is gathered about the patients participating.

However, things are getting more complicated now — which in this case is good. There may be a way to make the timing more personally tailored. Indeed, it appears that some people may do better to use light therapy in the evening. You see, exactly how light therapy actually treats depression has not been fully established. However, excellent research in this area has begun to suggest that light therapy works by re-setting your biological clock timing (your “circadian rhythms”) toward where it should be. For some people with SAD, their timing can be set to something closer to July rather than where their body seems to go in November through February!

This research uses language that can be difficult to understand (said I, using my own difficulties with it as a guide — maybe you’d find it easier to follow than I have). It speaks of the timing of sleep compared to when your melatonin begins to go up in the evening. To make things easier, though, Dr. Terman’s group has produced a system for telling you when to use your light box.

Their research suggests that light therapy may work best about 8-9 hours after one’s body starts secreting melatonin.Terman

This hormone is associated with sleep, and the time at which it stops being produced may be one of the most important signals to the rest of your body saying “it’s daytime now, time to get up!”. When is your melatonin onset? What time does your body start its sleep cycle? One way to tell, according to Dr. Terman’s group, is to use a questionnaire they developed to determine whether you’re a “lark” or an “owl” — a morning person or an evening person. I’ll bet you have some guesses!

They call it the Morningness-Eveningness Questionnaire (MEQ) (if that link breaks, just search for the test by name at Brace yourself: if you’re an owl, you might be able to start your morning light therapy as late as 8 am and see full benefit. But if you’re a lark, there is some evidence (not conclusive yet) that you should be starting your morning light treatment as early as 4 am! Instead of trying to determine your hour of melatonin onset, and calculating 8-9 hours later as your light time, you can take the questionnaire. If it says you’re really a morning person, you may see more benefit from your light therapy by pushing the treatment time earlier, toward say 5 am anyway.

The MEQ-recommended time is the “sweet spot” where you’re likely to get the strongest effect. If you can’t get up that early, don’t sweat it, just get as close as you can, but not after 2:30 pm unless your doctor advices you to (and why would they? Well, some people have very unusual sleep schedules that might warrant that kind of custom tailoring).

Chronotherapy: an entire package of treatments for depression using light and sleep shifts

Chronotherapy puts light therapy together with sleep therapies to create a complete package treatment for depression that can replace or add to medication approaches. The
ingredients include:

  1. Wake therapy
  2. Sleep phase advance
  3. A light box
  4. A dawn simulator

You’ve already learned about light boxes and dawn simulators above. For more on the first two ingredients, see my page on Chronotherapy.

Warning: excruciating details below . . .

White vs. Blue, and Safety

(go read some other page; this is only for the really interested)

This issue of eye safety cranked up recently with the arrival of the little blue light box. Back in 1992, a team of light researchers estimated that it would take 72 winters of daily 30-minute light therapy to reach the threshold for causing eye damage.Waxler But because the blue box puts out a wavelength that is theoretically more harmful than other wavelengths, there’s been a lot of interest in the safety issue lately. Ironically, the graphs below suggests that if anything, the blue box is safer than “full spectrum” or all-white units.

Output of energy by wavelength: Full spectrum boxes

From left to right on this graph are the colors of the visual spectrum of light (part of the larger “electromagnetic spectrum” which includes ultraviolet, which would be off this graph to the left; and infrared, which would be off this graph to the right).  Blue is between 450 and 500 nm (nanometers).

The black curve  is sunlight. The blue hump is the output from one of the little blue light boxes. The red and green curves are two different “full spectrum” light boxes.

(updated 10/2020)

Dark Therapy

A simple fix for one of the underlying causes of bipolar disorder. Here’s how dark therapy began, and where it is today.

Read More »

Fish Oil Dose

There’s not much question that fish oil is better than a placebo. Until recently there was a big question about dose, but the review below

Read More »

Get Smarter About Mental Health

Our Brain Bulletin decodes mental health updates for you.

It’s free.