(2020-12-19) Alexander Light Therapy

Scott Alexander on Light Therapy. The short version: Light therapy can treat seasonal affective disorder (SAD) (eg winter depression) and sometimes regular depression. Buy this light box, and at some time between 6 AM and 9 AM, sit exactly 12 inches away from it and do some activity that doesn’t involve staring directly at the light box. Continue every morning for the period of time you’re at risk of depression. If bipolar, don’t try this without medical supervision. Carex Day-Light Classic Plus Sunlight Therapy Lamp - 10000 LUX Therapy Lamp at 12 Inches, LED Bright White Light with Adjustable Height and Brightness Levels for Mood, White

The long version:

1. Why does light therapy work?

The most important effect of light therapy is coordinating your circadian rhythm.

The rhythm is set by the suprachiasmatic nucleus of the hypothalamus (aka the “body clock”), but it is not actually very good at this and on its own is likely to mess up by about an hour a day. In order to calibrate itself, it relies on external cues – most importantly sunrise and sunset times, but also social cues like going to work, eating meals, et cetera.

depression can be both a cause and an effect of circadian dysfunction.

Humans evolved in Africa where the days are mostly the same length throughout the year, and our circadian clocks are not really prepared for northern latitudes where the days are very short in winter and very long in summer.

Aside from all this, a secondary effect of light therapy is just to make people happier and more energetic. Almost everyone is happier and more energetic on bright, sunny days, maybe because of an evolutionary program telling animals to be more active during good weather.

2. What are the different kinds of light therapy?

The two main kinds of light therapy are light boxes and dawn simulation.

Light boxes are extremely bright lights. They try to trick the circadian clock into believing it’s daytime by simulating one of the most salient features of daytime: sunlight. Normal indoor lights, even very bright indoor lights, are only about 1% as bright as the sun. Light boxes are brighter, around 10% as bright as the sun, and more likely to affect circadian rhythm.

Dawn simulators are lights that slowly shift color and brightness in the same pattern as a natural dawn.

Of the two methods, light boxes are better-studied, but dawn simulators will be more convenient for many people. Of two studies comparing them, one found light boxes were a bit more effective, and the other found dawn simulators were a bit more effective. Either would be an okay choice. If you are indecisive and want me to tell you which one to use, I recommend using light boxes because there’s more data.

3. When should I do light therapy?

You should do light therapy in the morning.

between 6 and 9 AM

some times in this window may be better than others. The absolute best time will be whenever your circadian clock is naturally programmed to expect sunrise. This is kind of unrelated to when the real sunrise is, and more related to whether you are an “early bird” or a “night owl”.

4. How do I do light therapy with a light box?

–4.1. What dose of light therapy should I start with?

The usual starting dose of light box therapy is 5,000 lux-hours daily.

The usual solution is to get 10,000 lux for half an hour. For most people, this works fine.

–4.2. What is the best brand of light box?

*Any brand is fine as long as it provides you the right dose.

Almost every brand claims to be “10,000 lux”. This claim is meaningless. Remember, lux is a unit of ambient brightness, not of the inherent power of a given light source.*

Reputable lights will give you a brightness and a distance, eg “10,000 lux at a distance of twelve inches”. I cannot stress this point enough

The two most informed consumer reviews of light boxes, NYMag Strategist’s and New York Times Wirecutter’s, both recommend as their first choice the Carex Daylight Classic Plus, which costs $150 off Carex’s website and $115 on Amazon. I agree.

it gives the distance at which its light box provides 10,000 lux, and that distance is a manageable/comfortable 12 inches. This product is large and bulky, but that’s because it actually tries to deliver on its claims; the many smaller and more convenient light boxes you can find around mostly don’t work.

–4.3. How do I use the light box?

Once you have a time and a distance, go to that distance at that time and turn on the light box. Do not stare at the light box directly; this will damage your eyes. Just do whatever you would normally be doing, in the much brighter environment of being close to a light box

–4.4. What are light glasses?

In theory these ought to work, since they’re providing the same treatment as light boxes through a different delivery system, but I don’t know of any really strong research demonstrating that they do

–4.5. What if I don’t feel better at the standard dose?

Like any other time you don’t improve on a standard dose of medication, you might want to consider raising the dose.

–4.6. What if I’m sure I have seasonal depression, but no dose of light therapy works for me?

Unfortunately, many of the researchers and companies operating in this space are morons and refuse to make light boxes brighter than 10,000 lux. If you’re one of the people with this problem, you have a few options.

You could try sitting closer to your light box

You could try buying multiple light boxes

Or if you’re handy, you could try building a very very very bright light.

David Chapman writes about his experience building a 30,000 lumen light which provides 30,000 lux at a distance of two feet

More recently, he built this kind of extreme 90,000 lumen lamp, which provides ~25,000 lumen level lighting to a whole room

Eliezer Yudkowsky built another light to treat his partner’s seasonal affective disorder unresponsive to standard light boxes. He doesn’t have a good estimate of how many lux it provided but it must have been more than 10,000;

–4.7. Are light boxes safe? What if they damage my retina or something?

The SKY PORTAL is a light-box-like product capable of producing 60,000 lux at standard-light-box-distance, and may also mimic the color spectrum of sunlight better than other products, but it costs $1100 and is made by an individual who could best be described as “eccentric”.

Any light box with a spectrum different from normal daylight might potentially be more dangerous than going outside on a sunny day. I haven’t really seen any evidence of this, but I guess it’s something you could be concerned about.

5. What are dawn simulators?

Dawn simulators are lights that try to imitate sunrise

6. Can I use a dawn simulator to start, and then a light box once the dawn simulation is complete?

In theory this ought to work very well, but nobody has studied it, and there is no product that automatically combines both functionalities. If you are a light box manufacturer, consider this a feature request.

7. What conditions can I use light therapy for?

Light therapy is most commonly used in winter depression

Various studies suggest that light therapy works about as well as antidepressants for regular unipolar depression, and that light therapy taken with antidepressants can make the antidepressants work more quickly.

Various people make all sorts of unsubstantiated claims that it can help with anxiety, obsessive-compulsive disorder, and eating disorders. None of these have really been well-established, although night eating syndrome has a clear circadian component and it would not surprise me at all if light therapy helped.

Some completely healthy people find light therapy helps them feel more awake in the morning and be more productive during the day. Dawn simulators work well as unusually gentle alarm clocks that help your body feel “ready” to wake up,

8. How do light boxes and dawn simulators compare to natural sunlight?

Natural sunlight is better

This is important if you’re using light therapy for something other than seasonal affective disorder. Some people, in the middle of summer, sit by a light box in the morning in order to help with their depression. This could work. But it will work less well than sitting outside in the bright summer sunlight at the same morning hour

9. Can I try this on my own, or do I need a doctor or psychiatrist helping me?

If you’ve read this document, you already know more than 95% of psychiatrists about light therapy.

The only exception is if you’re bipolar.