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How Does Light Therapy Help Treat Depression?

What is Light Therapy?

Light therapy, also known as phototherapy, is a type of treatment that is used in the treatment of depression. Light therapy involves exposure to an artificial source of light that mimics natural sunlight. (1, 2, 3) This type of therapy is primarily used in the treatment of major depressive disorder (MDD) with seasonal patterns. This type of depression was earlier known as seasonal affective disorder (SAD). This type of depression that occurs only at a certain time of the year, typically in the fall and winter months when the days are shorter, and there is less sunlight. (4, 5, 6)

Light therapy is also used for the treatment of other medical conditions, including sleep disorders, jet lag, and other forms of depression.

How Does Light Therapy Help Treat Depression?

A lot of research has been carried out on how light therapy helps in the treatment of depression. This research on light therapy has provided a few reasons as to why it helps improve the symptoms of depression. (7, 8) Some of the reasons behind this include:

  • Light therapy works on the body’s biological clock and helps align the brain’s 24-hour cycle or the circadian rhythm.
  • It contributes to consistent and stable sleep patterns.
  • It increases alertness.
  • It helps balance out the activation of serotonin circuitry in the brain, which is known to be an important component in mood regulation.(9)

However, it is important to keep in mind that the exact extent to which light therapy works in treating depression depends a great deal on the light wavelength, duration of use, as well as your individual circadian rhythm patterns. Circadian rhythms are cycles of essential body functions that take place over a 24-hour cycle, and it is known to affect the body’s hormones, eating habits, and sleep schedules as well.(10)

How Does Light Therapy Work?

Light therapy works by compensating for the lack of exposure to natural sunlight, which is believed to be the main contributor to major depressive disorder with seasonal patterns. During a session of light therapy, you have to sit near a sun lamp or a lightbox that gives off a bright light. This lamp or box has been designed to mimic natural sunlight. However, there are several variations between these devices depending on different manufacturers.

The standard output of a light therapy lamp is ideally in the range of 2,500 to 10,000 lux. A lux is the unit of measurement for light brightness.(11)

Treatments for depression using light therapy tends to typically start in the fall and continue until early spring. The duration of the treatment session depends on how well you handle the treatment, along with the strength of the lightbox.

Guidelines for treatment with bright light therapy typically starts with 10,000 lux for at least 30 minutes every morning. However, someone new to this treatment method may need to take shorter initial treatments. The more powerful is the lightbox being used during the therapy session, the shorter the treatment session is likely to be.

Are There Are Side Effects of Light Therapy for Depression?

Some people should not use light therapy, especially those who have medical conditions that make the eyes sensitive to light, or they are on medications like some antipsychotics or antibiotics that increases sensitivity to light. (12, 13)

If you are thinking about undertaking light therapy for depression, you should first consult a doctor, especially if you have any of the following medical conditions:

  • Eye conditions
  • Sensitive skin
  • A history of skin cancer

In some cases, individuals may experience irritability or a sense of euphoria, which is typically a sign that you should stop using the lamp and consult your doctor once. (14)

For those people who can use light therapy, there still can be some potential side effects. Usually, these can be fixed simply by adjusting the intensity, duration, or timing of the sessions. Some of these side effects may include:

If you experience any of these or any other side effects, discuss them with your doctor, but it is likely that you may find relief by making some minor changes to your light therapy routine. It is recommended that you avoid using the lamp before going to bed to prevent insomnia, and also keep the lightbox at some distance away from you to avoid headaches and eyestrain.

Pros and Cons of Light Therapy for Depression

Apart from the many benefits in the improvement of depression symptoms, light therapy is also very easy to begin and adjust as per how you feel while using this form of treatment. Some of the advantages of light therapy include:

  • The treatment is easily accessible, and it can be done at home. You can either purchase your own lamp or lightbox, or it is also possible to rent a lightbox.
  • The treatment is non-invasive, and it provides an alternate or add-on medical intervention to the medications. There is no need to take this form of therapy internally.
  • Even though some potential side effects might be there, especially if you use the lamp incorrectly, light therapy is generally considered to be a low-risk and safe form of treatment.
  • It is a highly convenient form of treatment for depression as you can use light therapy at home while reading or having your breakfast. You can even stop the therapy for a couple of days without experiencing any adverse side effects or the return of your symptoms.
  • Most of the side effects of light therapy, like dizziness, headache or nausea, can be prevented simply by adjusting how you use the lightbox or lamp.

Light therapy also has many potential uses beyond treating major depressive disorder with seasonal patterns. However, before starting any new therapy, it is ways better to discuss it with your doctor first. (15)

There are some negative aspects of light therapy as well. These include the side effects and complications that may occur, including:

  • Insomnia
  • Fatigue
  • Headache
  • Eyestrain
  • Irritability
  • Euphoria

It is also important to know that insurance might not cover the cost of buying a light therapy lamp, even if your doctor has prescribed it. This expense sometimes acts as a barrier for many people.

Also, achieving positive results with a light therapy lamp may take some time, at least a couple of days. Reaping the benefits from the lamp will need you to use it consistently and at the same time every day.

What Does The Science Say About Light Therapy?

Light therapy can be used as an add-on or a stand-alone treatment for depression. Most of the research on light therapy has been on the use of this therapy for treating major depressive disorder with seasonal patterns or seasonal affective disorder. In recent times, academic research has also begun to focus on the use of light therapy for other medical conditions, including sleep disorders, dementia, and other mood disorders.(16, 17)

Some medical experts have also suggested that light therapy can be used in combination with other treatments like psychotherapy or medications. The basic idea behind this is to use it as a supplemental therapy. So, in addition to treatment, people suffering from depression in the fall and winter months should try to remain more physically active. Winter is a season when people tend to become more sedentary and avoid going outside in the cold. Getting more exercise can help boost your mood.(18)

A study carried out in 2016 and published in JAMA Psychiatry found that light therapy, either alone or carried out in combination with the antidepressant drug Prozac (fluoxetine), was effective in improving the symptoms of depression. The study was carried out on 122 participants who had major depressive disorder.(19)

In 2017, a trial of people having bipolar I or II disorder found that light therapy helped improve the remission rates of depression and also reduced depression rates over a six week trial period. In the trial, light therapy was an adjunct to the bipolar disorder treatment, and the researchers did not observe any changes in mood polarity of the participants.(20)

How Can You Do Light Therapy At Home?

Before beginning light therapy at home, it is a good idea to consult your doctor or a mental health professional who will be able to give you the proper guidelines on how to do light therapy. It is important to remember, though, that light therapy may interact with other treatments that you are presently on, such as medications. This is why you should only do light therapy after your doctor has signed off on the same. And also after reading the instructions provided by the manufacturer of the lightbox.

If you are using a lamp with lower intensity, it may require you to stay near the light for a longer time. The instructions by the manufacturer can also help you determine any specific risks and hazards associated with that lamp.

To use light therapy with a lamp of 10,000 lux intensity at home, here are the steps:

  1. Place the lamp on your desk, counter, or any other surface.
  2. Stand or sit at the correct distance away from the lamp as advised by the manufacturer or your doctor.
  3. Keep your eyes open and avoid falling asleep during the light therapy sessions.
  4. Do not stare directly at the lamp or lightbox.
  5. Begin your sessions with 30 minutes of exposure time every day.
  6. Schedule your light therapy sessions as soon as possible after you wake up in the morning, preferably between 6.00 a.m. and 9.00 a.m.

How Long Does It Take For Light Therapy To Help With Depression?

Many people end up experiencing benefits from light therapy within just a few days. Typically, the symptoms of depression should start to improve in around two to three weeks. If there is no improvement, though, you can increase the time you spend in front of a 10,000 lux lamp to up to 60 minutes a day. If this also does not work, you should consult your doctor again for the advice.

If you find that light therapy is helping you, you may consider making some changes to your schedule. For example, you can decrease the time you spend in front of the lamp to 15 to 20 minutes or even schedule it at a different time of the day.

If the therapy is working for you, you can even consider taking a break from light therapy for a day or two. However, most people with major depressive disorder with seasonal patterns continue using light therapy regularly over the winter months to prevent their symptoms from coming back.


Light therapy is a commonly used treatment option for the treatment of major depressive disorder with seasonal patterns, other types of depression, dementia, and sleep disorders. It is most often found to be effective. Experts believe this is due to the effects light therapy has on your body’s circadian rhythm and levels of serotonin in the brain. Some people, however, may experience some potential side effects, but most of these are usually mild and can be prevented. Before beginning light therapy, it is a good idea to speak with your doctor to confirm if light therapy is a good treatment option for you.


  1. Terman, M., 2007. Evolving applications of light therapy. Sleep medicine reviews, 11(6), pp.497-507.
  2. Hamblin, M.R. and Demidova, T.N., 2006, February. Mechanisms of low level light therapy. In Mechanisms for low-light therapy (Vol. 6140, p. 614001). International Society for Optics and Photonics.
  3. Golden, R.N., Gaynes, B.N., Ekstrom, R.D., Hamer, R.M., Jacobsen, F.M., Suppes, T., Wisner, K.L. and Nemeroff, C.B., 2005. The efficacy of light therapy in the treatment of mood disorders: a review and meta-analysis of the evidence. American Journal of Psychiatry, 162(4), pp.656-662.
  4. Terman, M., Terman, J.S., Quitkin, F.M., McGrath, P.J., Stewart, J.W. and Rafferty, B., 1989. Light therapy for seasonal affective disorder. Neuropsychopharmacology, 2(1), pp.1-22.
  5. Glickman, G., Byrne, B., Pineda, C., Hauck, W.W. and Brainard, G.C., 2006. Light therapy for seasonal affective disorder with blue narrow-band light-emitting diodes (LEDs). Biological psychiatry, 59(6), pp.502-507.
  6. Wileman, S.M., Eagles, J.M., Andrew, J.E., Howie, F.L., Cameron, I.M., McCormack, K. and Naji, S.A., 2001. Light therapy for seasonal affective disorder in primary care: randomised controlled trial. The British Journal of Psychiatry, 178(4), pp.311-316.
  7. Maruani, J. and Geoffroy, P.A., 2019. Bright light as a personalized precision treatment of mood disorders. Frontiers in psychiatry, 10, p.85.
  8. Tuunainen, A., Kripke, D.F. and Endo, T., 2004. Light therapy for non‐seasonal depression. Cochrane Database of Systematic Reviews, (2).
  9. Harrison, S.J., Tyrer, A.E., Levitan, R.D., Xu, X., Houle, S., Wilson, A.A., Nobrega, J.N., Rusjan, P.M. and Meyer, J.H., 2015. Light therapy and serotonin transporter binding in the anterior cingulate and prefrontal cortex. Acta Psychiatrica Scandinavica, 132(5), pp.379-388.
  10. 2022. [online] Available at: <https://www.nigms.nih.gov/education/fact-sheets/Pages/circadian-rhythms.aspx> [Accessed 15 February 2022].
  11. Psychiatric Research and Clinical Practice. 2022. Commercially Available Phototherapy Devices for Treatment of Depression: Physical Characteristics of Emitted Light | Psychiatric Research and Clinical Practice. [online] Available at: <https://prcp.psychiatryonline.org/doi/10.1176/appi.prcp.2019.20180011> [Accessed 15 February 2022].
  12. Kogan, A.O. and Guilford, P.M., 1998. Side effects of short-term 10,000-lux light therapy. American Journal of Psychiatry, 155(2), pp.293-294.
  13. Levitt, A.J., Joffe, R.T., Moul, D.E., Lam, R.W., Teicher, M.H., Lebegue, B., Murray, M.G., Oren, D.A., Schwartz, P., Buchanan, A. and Glod, C.A., 1993. Side effects of light therapy in seasonal affective disorder. The American journal of psychiatry.
  14. Sad.psychiatry.ubc.ca. 2022. Instructions for using a light box | UBC Mood Disorders Centre SAD Information. [online] Available at: <https://sad.psychiatry.ubc.ca/resources/public-resources/light-therapy-procedure-for-using-the-10000-lux-fluorescent-light-box/> [Accessed 16 February 2022].
  15. Campbell, P.D., Miller, A.M. and Woesner, M.E., 2017. Bright light therapy: seasonal affective disorder and beyond. The Einstein journal of biology and medicine: EJBM, 32, p.E13.
  16. Campbell, P.D., Miller, A.M. and Woesner, M.E., 2017. Bright light therapy: seasonal affective disorder and beyond. The Einstein journal of biology and medicine: EJBM, 32, p.E13.
  17. Forbes, D., Culum, I., Lischka, A.R., Morgan, D.G., Peacock, S., Forbes, J. and Forbes, S., 2009. Light therapy for managing cognitive, sleep, functional, behavioural, or psychiatric disturbances in dementia. Cochrane database of systematic reviews, (4).
  18. Pinchasov, B.B., Shurgaja, A.M., Grischin, O.V. and Putilov, A.A., 2000. Mood and energy regulation in seasonal and non-seasonal depression before and after midday treatment with physical exercise or bright light. Psychiatry research, 94(1), pp.29-42.
  19. Lam, R.W., Levitt, A.J., Levitan, R.D., Michalak, E.E., Cheung, A.H., Morehouse, R., Ramasubbu, R., Yatham, L.N. and Tam, E.M., 2016. Efficacy of bright light treatment, fluoxetine, and the combination in patients with nonseasonal major depressive disorder: a randomized clinical trial. JAMA psychiatry, 73(1), pp.56-63.
  20. Sit, D.K., McGowan, J., Wiltrout, C., Diler, R.S., Dills, J., Luther, J., Yang, A., Ciolino, J.D., Seltman, H., Wisniewski, S.R. and Terman, M., 2018. Adjunctive bright light therapy for bipolar depression: a randomized double-blind placebo-controlled trial. American Journal of Psychiatry, 175(2), pp.131-139.

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Sheetal DeCaria, M.D.
Sheetal DeCaria, M.D.
Written, Edited or Reviewed By: Sheetal DeCaria, M.D. This article does not provide medical advice. See disclaimer
Last Modified On:February 21, 2022

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