Light Therapy

Our rating
Seasonal depression 2 smilies: This treatment is useful. It is supported by scientific evidence as effective, but the evidence is not as strong.
Non-seasonal depression 1 smiley:  This treatment is promising and may be useful. It has some evidence to support it, but more evidence is needed to be sure it works.


The rating system

  • 3 smiliesThese treatments are very useful. They are strongly supported as effective by scientific evidence.
  • 2 smiliesThese treatments are useful. They are supported by scientific evidence as effective, but the evidence is not as strong.
  • 1 smileyThese treatments are promising and may be useful. They have some evidence to support them, but more evidence is needed to be sure they work.
  • No smiley On the available evidence, these treatments do not seem to be effective.
  • Question markThese treatments have not been properly researched. It is not possible to say whether they are useful or not.
  • Exclamation MarkSafety or other concerns have been raised for the use of these treatments.

What is it?

Light therapy involves exposure to bright light for around 2 hours each day, usually in the morning. Light therapy can involve exposure to natural sunlight, but more often involves using a lamp-like device called a light therapy box, or a bank of fluorescent lights, which emit a bright light.

How does it work?

Light therapy is mainly used for people who tend to become depressed in autumn and winter, when the daylight is shorter. These people then get better in spring and summer. This type of depression is knows as seasonal affective disorder (SAD). The lack of light in winter is thought to affect their natural body rhythms. During light therapy, the person undergoing therapy sits near a light therapy box for a few hours, which mimics the type of exposure to natural light that they would get during spring and summer months.

Light therapy is sometimes also prescribed for people with non-seasonal depression.

Is it effective?

There is good evidence that light therapy helps people with seasonal affective disorder. Studies have found that light therapy works better than placebos (treatments with no known effect) and can be just as effective as antidepressant drugs. There is also evidence that using light therapy as well as antidepressant medication is more effective than using either treatment by itself. Light therapy works best if given early in the morning rather than later in the day. There is less evidence on whether light therapy is effective at preventing SAD.  

There is less evidence on whether light therapy helps people whose depression is not seasonal. However, a small number of studies show that it could be beneficial.

Are there any disadvantages?

Light therapy can produce mild mania (over-excitement) in some people. Some people might also experience problems in getting to sleep at night. However, light therapy is generally well tolerated and is associated with fewer side effects than antidepressant medication.

Where do you get it?

Equipment such as light boxes and dawn simulators are available to buy online. You can also usually get a good amount of light exposure by going outside for one or two hours in the morning, but this might not be possible in countries that have very short winter days.


Light therapy is one of the best treatments for seasonal depression and may also be helpful for other types of depression.

Key references

  • Lam RW, Levitt AJ, Levitan RD, Enns MW, Morehouse R, Michalak EE, 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. Am J Psychiatry. 2006 May; 163(5): 805-12.
  • Geoffroy PA, Schroder CM, Reynaud E, Bourgin P. Efficacy of light therapy versus antidepressant drugs, and of the combination versus monotherapy, in major depressive episodes: A systematic review and meta-analysis. Sleep Medicine Reviews. 2019; 48: 101213.
  • Nussbaumer, B., Kaminski-Hartenthaler, A., Forneris, C. A., Morgan, L. C., Sonis, J. H., Gaynes, B. N., Gartlehner, G. (2015). Light therapy for preventing seasonal affective disorder. Cochrane Database of Systematic Reviews(11).
  • Tuunainen A, Kripke DF, Endo T. Light therapy for non-seasonal depression (Cochrane Review). In: The Cochrane Library, Issue 3, 2004. Chichester, UK: John Wiley & Sons, Ltd.

Last reviewed and updated: 1 November 2019