Workstation with 90,000 lumens of bright lights for winter depression therapy
Wombat accessory optional but highly recommended

Not getting enough daylight causes the winter blahs. Supplementing winter daylight with seriously bright indoor light lessens or eliminates the blah.

You may need a lot of supplementation for that—way more than ordinary indoor lights can produce. Probably also way more than “light therapy lamps” provide.

Winter blahs range from barely noticeable to severe. You may just feel a little less motivated in November than May. You might feel vaguely offish in winter. You might feel less ebullience and enjoyment. You might not be quite as creative, or get as much done.

At the other end of the spectrum, for some it means crippling depression that requires urgent medical treatment to avoid hospitalization or worse.

Mine never got to that point, but it was closer to the bad end than the other. Before I figured out how to chase it away with seriously bright light supplementation, I was quite unhappy every winter, and I couldn’t get much done from November through January. Now, so long as I remember to turn the lights on, I feel normal, upbeat, and productive all winter long.

Adequate light supplementation has been a radical improvement in my life, as it has been for some other people. I want to raise awareness of the possibility, and give you the information you need to act on it if it seems like it might be relevant for you.

Would it make a difference for you? Unless you experience severe depression, science is silent. We know it works for that, but regular winter blahs? There’s little data. And, you shouldn’t take my word for it; I’m some random guy on the internet.

Instead, you may be inspired by your own experience:

If so, serious light supplementation may work well for you.

Winter blahs vs. seasonal affective disorder

The medical profession calls severe winter blahs seasonal affective disorder (SAD). Officially, to count as SAD, you have to meet the criteria for “major depressive disorder,” which is quite bad. Informally, though, many laypeople refer to any degree of winter blues as “SAD.”

Doctors recommend bright light therapy as the standard treatment for SAD. This is on the right track, but I have two objections.

Taking a supplement, though, seems natural. Most people don’t get enough magnesium in our diets, and taking magnesium supplements is sensible. Maybe most Americans—except in the southernmost states—and most Europeans don’t get enough light in winter. So, taking a supplement seems sensible.

Lux are the measure of how much light you get. Summer sunlight is about 100,000 lux. An overcast winter day is 1,000 to 2,500 lux. This is a huge difference! It may not be so obvious because our eyes’ irises open and close to partially—but not completely—compensate.

Adequate supplementation means getting something more like 100,000 lux than 1,000. The medical recommendation for SAD treatment is 10,000 lux for at least half an hour each morning. I’ve found I need more than that.

Typical indoor lighting is 100–500 lux. That means a conventionally “brightly lit room” gives you less than one percent as much light as summer sun. You cannot adequately supplement your light needs by merely doubling the number of lamps you have, or by putting 120 watt bulbs in place of 60 watt ones.

YOU NEED MORE LUX. You need industrial strength supplements. A follow-on web page, “Seriously bright light vs. the winter blahs,” explains how, practically, you can get them.

This one explains:

What bright light supplementation may do for you

There seems to be wide individual variation in how much light people need to feel normal, happy, and productive.1 I would guess how much light you need corresponds to how bad your winter blahs get. (There’s no science on this yet.)

For example, my spouse’s winter blahs are usually quite mild, and can be reversed with about half as much light as I need. That’s still much more than you can get from ordinary household lighting. (The next page explains how you can get it.)

There is pretty good scientific evidence that moderately bright light effectively treats both mild “winter blues” and major clinical depression.2 This is now quite widely known, and bright light therapy is the mainstream medical recommendation.

So why doesn’t everyone do that? Why are winter blahs still common? My guess is three reasons:

  1. The amount of light delivered in the scientific studies is only barely enough to be effective.
  2. Most of the “SAD lights” people buy give much less light even that that. People try them and conclude “didn’t work for me”—but those things probably wouldn’t work for anyone.
  3. Using even the brightest ones is awkward, unpleasant, and a hassle, so people don’t bother.

It seems reasonable that all three factors could be addressed with much brighter light. It seems reasonable that would be more effective. Unfortunately, there is currently no scientific evidence for this, because no one has done the experiment.3

My belief that brighter light is more effective is based on common sense; my personal experience; and the experience of many other people who have written on the internet that it works for them. We could be fooling ourselves. It’s easy to do that—to believe taking a herbal supplement is curing your cold when it’s not, for instance.

On the other hand, if you take a January flight to Hawaii4 and get off the plane around noon, and walk out into the sun, you may have an immediate sense of “Ooooh… yes, THIS is what I needed.” There’s a feeling of instantaneous relaxation and general okayness.

You can get a sense too from the picture at the top of this web page. This was a rig I built in 2016, using less good technology than is available now, but you can see that in a dark living room the workstation is lit so brightly that the camera’s image washed out. I wasn’t able to measure it directly, but I estimated 25,000 lux.

It’s possible now to light a whole room like that. What is it like to walk into a room that’s bright as day when it’s fully dark outside at five p.m.? It’s nice. It feels cheerful and uplifting and comforting and energizing—like walking into the sun at the beginning of your vacation.

When I’ve had guests over, some can’t tear themselves away from the brights and just want to bask in them all day.5 Several times in winter, people from the neighborhood have rung the doorbell in the evening to say “Uh, sorry to intrude, but—your house always has this radiance pouring out from the front window, and, well, we couldn’t help wondering how you do that!” And I showed them the set-up, and they looked so wistful and said “thank you… that is wonderful… we couldn’t do that.”

You can do that—but it will take some work, which the follow-on page explains. It takes much less work than it did a few years ago, because lighting technology keeps improving. And you can start with a quite simple set-up, see how it works for you, and then add to it if—as I suspect—you find you want more.

The biology of the winter blahs

This is fascinating to me, but if you’re not so interested in why bright light supplementation works, you can skip ahead to the practical “How to make bright light supplementation work for you” section.

Most mammal species slow down during the winter.6 They are much less active, sleep much more, and eat as much as they can when they can get it, because food supplies are unpredictable. Hibernation is an extreme of this.

The winter blahs are the human version. Seasonal affective disorder is the extreme; those afflicted feel like they want to hibernate, although that’s not possible for humans.

For me, at least, it is not primarily affective (meaning about mood). My brain slows down after the equinox, and—without supplementation—by early December it’s impossible to get anything done. I used to get depressed in winter, but I think that’s mostly because I was upset not to be able to think properly or to accomplish anything.

In the last few years, biologists have discovered most of an explanation for how this works. These discoveries have significant implications for the kind of lighting that is most effective for supplementation, and how best to use it.

You may remember that your retina has cone cells (which sense color) and rod cells (which pick up fine details of what you are looking at). It turns out that there is a third type of light-sensitive cells in the retina, which aren’t mainly used in vision, but instead just tell the brain whether it is daytime.7 These cells connect directly to the parts of the brain that maintain circadian rhythm (the cycle of day and night), alertness, sleep, and aspects of mood.8

Critically, these cells sense sky blue light; they don’t pick up on other colors much. They are highly sensitive to just how bright the light is. And, they are absent in the fovea (the center of your vision), but are roughly evenly spread across the rest of the retina (like peripheral vision). These make sense for a daylight sensing system!

The biological facts imply that supplementary artificial lights need to include plenty of blue in their spectrum, need to be bright enough to fool the brain into thinking it’s daytime, and should light up your entire visual field rather than just being bright in a small area.

For mammals that need to slow down for winter, what are the seasonal clues? Day length may be the most important one. Depending on your latitude, there are many fewer hours of daylight at midwinter than at midsummer. Unsurprisingly, it seems the same system that synchronizes your brain’s daily cycle by detecting daylight also tells it what time of year you are in.9 Winter sun is also less bright than summer sun (another clue that could be detected by this same system). The angle of the sun in the sky is an additional clue.10 All these also have implications for light supplementation.

How to make bright light supplementation work for you

The main supplementation strategy is to fool your brain into thinking it’s summer by simulating daylight for twelve-plus hours, centered around the middle of the day. This means adding daylight-like light before the actual dawn, and/or after dusk.11 Depending on circumstances, adding bright light in the middle of the day may help too. I turn my bright lights on as soon as I wake up, and as soon as it starts to get dark outside, and also during the rest of the day if it’s gloomy outside. I typically wake around 6 a.m., and run the lights until about 8 p.m, for a roughly fourteen hour artificial day length.

People who suffer from seasonal affective disorder tend to develop longer-than–24-hour circadian cycles, resulting in “permanent jetlag,” with difficulty waking and difficulty getting to sleep at a regular hour. Sufficiently bright light first thing in the morning has been shown to fix this.

Relatedly, it’s important to not expose yourself to bright light, and especially not to blue light, after your artificial dusk time (8 p.m. in my case). That messes up your circadian rhythm, makes it hard to get to sleep, and appears to cause depression directly (in mice, anyway). I recommend using a setting or app on all of your screen devices that cuts blue light in the evening. (On Apple devices, this is called “Night Shift,” and you can find it in the Settings menu.) Set this for a custom schedule that matches your artificial day length, rather than using its default, which is the local natural day length. Eliminating the blue in the screen makes everything look orange, like sunset, which tells your circadian rhythm system it’s time to wind down.

The sun is much lower in the sky in winter. I know of no scientific evidence, but subjectively this seems to contribute significantly to the blahs. I have also found that arranging artificial bright light so that it comes from well above eye level makes it more pleasant and more effective.

If it’s quite a way above you, a bright light can illuminate a broader area, so there’s less sense that you are sitting in the dark with a bright light shining only on your face. Subjectively, the experience seems much more natural. I think this is due to the peripheral vision effect: bright light spread over the whole of your retina is more effective than the same amount concentrated in a small area. There’s only about a thousand of the daylight-sensing cells, and I suspect it’s important to stimulate as many of them as possible.

Advice on buying an official light therapy light, if you insist

I recommend against buying anything sold as a “light therapy lamp” or “SAD light.” They are underpowered, overpriced, and the advertising claims made for them are misleading, bordering on fraudulent—as I’ll explain at in the next section.

However, you may be more comfortable buying something recommended by supposed experts, instead of me. Until recently, the top recommendation on reputable review sites such as Wirecutter and The Strategist, based on interviews with medical specialists, was the North Star 10,000 light box. This is also the only “light therapy lamp” I would recommend, because it’s the only one I’ve found that is bright enough.

Unfortunately, it costs more than three hundred dollars, which probably seems like too much to most people. I’d guess that’s the reason the review sites have dropped it as a recommendation. It is too expensive. The second web page in this series explains how you can get more light than the North Star 10,000 for less than $100, using lamps made for other purposes.

The North Star is closely modeled on the light boxes used in the original 1980s research on seasonal affective disorder. That makes it a conservative choice: we know it works—somewhat, for some people, at least. It’s much brighter than anything else sold for light therapy now. I had one very much like it in the early 2000s,12 and I can also confirm personally that it did work—somewhat. I’d say it restored about a third of my typical winter mood and productivity loss. I have found better solutions, discussed in “Seriously bright light vs. the winter blahs.”

Light therapy lamps are misleadingly marketed, and probably most don’t work

This final section explains why most SAD lamps are unlikely to do much (if anything). That may lead you to consider seriously the better alternatives.

There’s a tragedy here. We have a marketplace filled with hundreds of different products, of which the North Star is quite possibly the only one that works.

People with seasonal affective disorder, or just the winter blahs, don’t know whether bright light will work for them, so they’re reluctant to spend much money to find out. Unfortunately, you can’t make a bright enough light at a price people are willing to risk, so most light therapy lamps don’t actually work. That means people try one and decide it’s useless (which it is) and give up.

I’m really mad about this; false advertising by the manufacturers has made effective solutions unavailable. Unavailable, that is, unless you are willing to bypass their products altogether and try something quite different—as I explain in the next web page!

10,000 lux: you won’t get that

10,000 lux!” proclaim all SAD lights. This is the main misleading claim. Nearly none of them can deliver that in reality.

Lux is a measure of how much light you get. It is not a measure of how much light a lamp puts out. How much light you get depends on how much it puts out, but also on how close you are to it. You would have to be unrealistically close to most SAD lamps to get the 10,000 lux they advertise.

10,000 lux is the amount aimed for in most scientific research on bright light therapy. Experts in the field continue to recommend 10,000 lux as the appropriate dose. Most research has been done with “light boxes,” which are metal cabinets, two feet by a foot in front, stuffed full of fluorescent tubes of the sort used in schools and offices before LED lighting came in. The North Star light box duplicates that.

These light boxes deliver 10,000 lux at a distance of two feet from your eyes. That is a realistic distance for a light on your desk.

Honest SAD lamp marketing specifies the distance at which they deliver 10,000 lux. The current expert recommendation, replacing the North Star, is the Carex Day-Light Classic Plus ($143 as of late 2023).13 It delivers 10,000 lux at twelve inches. I suggest you get a ruler, sit at your desk, put one end of the ruler next to your eye, and see where twelve inches reaches. You will find that it is not realistic that you’d put a lamp there. If you did, it would be quite difficult to do anything, even reading.

Eighteen inches is a realistic minimum distance from a lamp. Two feet is comfortable. At eighteen inches, you get less than half as many lux as at twelve. At two feet, you get one quarter.14 In reality, a “10,000 lux! (at twelve inches)” lamp delivers 2,500 lux. Still, that’s five times as much as typical indoor lighting, so it may do something.15

Most light therapy lamps are less bright than the Carex. Wirecutter bafflingly recommends the Verilux HappyLight Luxe ($70). It delivers 10,000 lux at six inches. (Imagine keeping a lamp six inches from your eyeball for any length of time!) That implies 1,250 lux at eighteen inches (a realistic minimum) or 625 lux at two feet (more likely the way it would get used in practice).

A light like this is not only too weak where you put it, it leaves the rest of the room dark. That feels unnatural, because there are pools of darkness all around it. Most of your peripheral vision doesn’t get the light—and the biology I discussed above, plus my experience and that of others, suggests that it’s peripheral vision that matters.

Less honest advertisers say only that their lamps “produce 10,000 lux,” which is impossible: no lamp produces any amount of lux.16 They don’t say anything about distance. However, in many cases, we can make a good guess about how powerful they are. The Verliux HappyLight draws 24 watts. Inexpensive SAD lamps often do say how many watts they draw, and the amount of light they produce will be nearly proportional.

An example is the SUXIO Light Therapy Lamp (about $20), which is currently the best selling one on Amazon. It draws 12 watts, half as much as the HappyLight, so it may deliver about 300 lux in realistic use. It seems unlikely to me that this has a significant effect. Another way of thinking about this is that a 12W LED produces as much light as a 75W incandescent bulb. Would adding one of those to your workspace make much difference?

The SUXIO has 1,488 ratings, averaging 4.3/5.0 stars. What are we to make of that? There are many possible explanations. Charitably, maybe the scientific research wildly overestimated how much light it takes to reverse SAD. Uncharitably, the ratings may be spam commissioned by the manufacturer.

Alternatively, consider Oscillococcinum, a homeopathic flu treatment. It has more than 26,000 Amazon reviews averaging 4.7/5.0. We know for sure that Oscillococcinum doesn’t do anything. (As the manufacturer’s spokeswoman said, “Of course it is safe. There’s nothing in it.”) Yet apparently millions of people swear by it. Why do people love treatments that definitely don’t work? No one knows! Fortunately we don’t need an answer, for our purposes. It’s sufficient to know that glowing Amazon reviews of a healthcare product do not imply it has any value whatsoever.

Analogously, the light dose delivered by most light therapy lamps is practically homeopathic, less than a tenth of what the medical science recommends.

Maybe the placebo effect will work for you! Or maybe you need way less light than I do!

Or maybe you’d do well to consider something that will deliver the medically recommended dose under the conditions you’d realistically use it in.

And, maybe you will find that 10,000 lux is good, but not as much as you’d ideally like. There’s nothing magic about this number. It was the most that was practical using fluorescent bulbs, which were the best lighting technology available when the early research was done. My personal experience, using LEDs instead, is that more than 10,000 lux is better.

But, maybe I and others who believe very bright light is more effective for us are fooling ourselves. Maybe we are like the people who take Oscillococcinum whenever they get a sniffle. Until someone sciences this, we can’t be sure.

Still… daylight is 100,000 lux; doesn’t that seem like it would be ideal?

Other misleading advertising claims

Light therapy lamps are just ordinary lights; there’s nothing special about them, except for the marketing.

Many advertise themselves as “UV-free.” This is effectively meaningless. Nearly all of them use LEDs as their light source. LEDs don’t emit any UV, so this is like advertising orange juice as “gluten-free.”17 This phrase is left over from fluorescent light boxes; fluorescent tubes do emit dangerous UV, so they need translucent plastic filters to stop it.

Many SAD lights advertise themselves as “full-spectrum.” This is a term with no specific definition. It is meant to suggest that the light emitted is similar to daylight—but that is actually false.

Daylight contains a lot of blue light, which is critical, due to the biology I described above. Daylight is “5600 K”—a measure of how much blue light it has, roughly speaking. Many inexpensive SAD lights are “3000 K” (almost no blue light) or “4000 K” (significantly less blue than daylight). This alone probably means they don’t work. I discuss this problem further here.

  1. 1.Some people actively prefer dim lighting. Some have reverse seasonal affective disorder: they get depressed in summer and are cheerful in winter. A friend with that condition says “in summer everything gets washed out by the glare, and I can’t see anything properly.” (This makes me wonder whether both conditions can result from inaccurate iris dilation—too little or too much.) My subjective experience is that I can’t see anything properly in winter, even though objectively my vision works fine and I can see the same things everyone else does. All the color seems drained from the world—and all its life with it.
  2. 2.For a recent review of the evidence, see for example Pjrek et al., “The Efficacy of Light Therapy in the Treatment of Seasonal Affective Disorder: A Meta-Analysis of Randomized Controlled Trials, Psychother Psychosom, 89:17–24, 2020. The evidence is only “pretty good” because most scientific studies have been of poor quality. Specifically, they didn’t include enough people to be really sure that the results were solid. Also, many studies have found only slight effects, or even none. My guess is that is because the lights they used weren’t nearly bright enough.
  3. 3.A pioneering 2022 study set out to test aspects of the hypothesis, but unfortunately due to methodological difficulties it gave no statistically significant comparative result, positive or negative. The paper is nevertheless well worth reading, for interesting discussion and an excellent literature review. Also, it cites an earlier version of this very web page—the one you are reading right now! Sandkühler et al., “100,000 lumens to treat seasonal affective disorder: A proof of concept RCT of Bright, whole‐ROom, All‐Day (BROAD) light therapy,” Depression and Anxiety 39:760–769.
  4. 4.It’s even more dramatic if you can fly to the opposite hemisphere, like San Francisco to Sydney, where January is high summer. Hawaii is still 21 degrees north of the equator, so that’s more like jumping to March than to July.
  5. 5.Ben Kuhn, similarly: “Everyone who’s visited my house after I installed the bulb has remarked on how cheery our living room now is, some of them before noticing the light. My partner and several friends are buying their own.”
  6. 6.Naturally, this is true only in places that have significant winters; it doesn’t hold for tropical mammals.
  7. 7.They’re called “intrinsically photosensitive retinal ganglion cells,” which is quite a mouthful.
  8. 8.A good recent review paper is Ludovic S. Mure’s “Intrinsically Photosensitive Retinal Ganglion Cells of the Human Retina,” if you want to dive into the details.
  9. 9.One piece of evidence is that the key protein in the daylight-sensing system is mutated in some people with SAD. Roecklein et al., “A missense variant (P10L) of the melanopsin (Opn4) gene is associated with Seasonal Affective Disorder.” SAD is highly heritable, and I would guess that other mutations elsewhere in the system account for most cases.
  10. 10.Temperature is of course also a major clue to season! I find that staying consistently warm helps significantly.
  11. 11.The original study on seasonal affective disorder had patients use light boxes for the three hours before dawn and the three after dusk. This is not practical for many people, and is probably more than necessary unless you live quite far north. On the other hand, the manufacturers of current SAD lights typically say “use for twenty to thirty minutes per day.” That might work for some people, I don’t know, but I suspect it is not nearly enough for most. I think they are trying to downplay the hassle factor, which might drive potential purchasers away.
  12. 12.There used to be several different makers of these; as far as I can tell, all the other brands have been discontinued.
  13. 13.The Carex uses fluorescent tubes, whereas nearly all other current SAD lights have switched to LEDs. It seems likely that the medical experts recommend it for that reason: it’s a conservative choice, because it’s closer to the fluorescent light boxes used in most research. However, I don’t believe it’s bright enough, and also daylight LEDs seem like they should be strictly superior to fluorescents, because they have more blue in their spectrum. That has not been validated in medical studies, however.
  14. 14.This is a somewhat simplified calculation using the inverse square law, which ignores reflected light. It’s the standard formula, though, and won’t be far off for most workspaces.
  15. 15.Some clinical research has been done targeting 2,500 lux rather than 10,000, and has also found that effective. I haven’t found a study that compared the two to see whether more is better. I believe it is.
  16. 16.The flashlight on your phone provides considerably more than 10,000 lux if you put it right next to your eyeball. (Please don’t test this! Or, at least if you do, be careful and move the light closer gradually. I am an idiot, and I wasn’t careful, and it was painful, and it took two solid minutes for the blind spot to return to normal.)
  17. 17.There are specialized LEDs that do emit UV, but they are expensive and definitely not used in SAD lights. Also, regular white LEDs do emit a very tiny amount of UV, but it’s so little that the relevant medical experts say it’s irrelevant.