Shall people use bright light therapy to treat depression?
Yes. If not for all the confirmatory research studies and meta-analyses, the Cochrane review (an independent analysis by British organization devoted to examining the medical proofs), concluded that “light therapy offers modest though promising antidepressive efficacy” in 2004. Since then, we have significant additional research complementing this finding.
Bright light therapy in practice
Besides all the research behind it, it is quite simple. You buy a lamp and let it shine on you regularly every day for a given amount of time. You may read, work, draw, or do whatever you want, so long as it keeps you sitting in front of the device. The only thing to do is to comply with the right amount of light and timing.
How much light and when: Treatment protocol for depression
If you are taking medications, you need to know the dosage of pills to take and when. In bright light therapy, the principle is very similar, the only difference being that the “strength” depends on two things: intensity of the light and duration of the exposure. Naturally, with more intense light you need less time and a weaker light should shine for longer.
The normal dosage is 10,000 lux for half an hour in the morning. Let’s explain it step by step:
Intensity of the light:
Normally you would opt for a lamp with 10,000 lux but it also may be less, possibly near 5,000. In fact, the actual intensity depends on how far from the lamp you are sitting, but you will be advised about the appropriate distance in the lamp’s manual.
- More than 10,000 lux is not recommended. Some research suggests that the brain would not respond any better to additional light over 10,000 lux anyway and your eyes might not be happy with such an intensity.
- Lamps with enhanced blue spectrum may be less intense because it is the blue part of the light that makes the difference. However, because studies differ in showing how much blue-enriched light is needed, and because this special light is less natural, there is no need to “go blue.”
- Another option is to buy bright light therapy glasses designed to shine the light directly into your eyes. However, be careful as the intensity would be different because the diodes are much closer to your eyes. Follow the advice of the manufacturer (or ask us!).
Time of exposure:
If you choose a 10,000 lux lamp, you should be exposed to the light for 30 minutes a day. If using 5,000 lux, it should be an hour. Correspondingly, the time increases for lower lux levels with 7,500 lux needing 40 minutes and 2,500 lux requiring two hours.
- Many people would be tempted to prolong the exposure thinking it maybe more effective. Indeed, we cannot rule this out – but neither can we confirm it. The proven effects are related to the established treatment protocols and there are no studies showing that higher exposure would have additional benefits. Of course, if you let it shine for ten more minutes, it is fine. But times higher exposure might come with unknown side effects. Simply: it is not tested and therefore not recommendable.
- One exception: If you have suffered with mania or hypomania before or have a close relative (parent, child, sibling) with bipolar disorder, you may start with the treatment gradually and keep track of possible signs of mania. Check the bright light treatment in bipolar!
You should use the lamp at a regular hour in the morning. Many people find it easiest to switch it on once they start working. Do not skip weekends in such a case!
- Again, there is one exception. In case you suffer predominantly from morning sleep problems (i.e. waking up too early), you would be better off using the lamp around noon. If, on the other hand, you cannot fall asleep in the evening but subsequently sleep well, you might benefit more from receiving the light exposure immediately after awakening.
For the whole duration of the depression and possibly further to prevent relapse using a lower intensity.
Device to choose
You should be exposed to 10.000 lux for half an our every morning. This, however, not only means that the lamp should emit light that has the intensity of 10.000 lux somewhere an inch or two from the diodes, but that this much light should really reach your eyes. Therefore, the manufacturer should not only inform about the intensity itself, but about the distance where you need to stay to get your 10.000 lux.
In particular, I would choose a lamp proven by the most successful studies on light therapy devices in depression. Particularly:
- The Carex Day-Light Classic Plus Bright Light Therapy Lamp was used in a clinical trial that found light therapy to be more powerful treatment of major depression than common antidepressants.
Adverse effects of light therapy
- Contraindications: in case of any problems with your eyes or retina, consult your ophthalmologist.
- Side effects: rare and mild.
- Pregnancy: bright light therapy is safe in pregnancy.
Maruani, Geoffroy (2019). Bright Light as a Personalized Precision Treatment of Mood Disorders. Frontiers in psychiatry.