Light therapy is generally safe. If side effects occur, they're usually mild and short lasting. They may include:

  • Eyestrain
  • Headache
  • Nausea
  • Irritability or agitation
  • Mania, euphoria, hyperactivity or agitation associated with bipolar disorder

When side effects do occur, they may go away on their own within a few days of starting light therapy. You also may be able to manage side effects by reducing treatment time, moving farther from your light box, taking breaks during long sessions or changing the time of day you use light therapy. Talk to your doctor for advice if side effects are a problem.

When to use caution

It's best to be under the care of a health professional while using light box therapy. It's always a good idea to talk to a doctor before starting light therapy, but it's especially important if:

  • You have a condition that makes your skin especially sensitive to light, such as systemic lupus erythematosus
  • You take medications that increase your sensitivity to sunlight, such as certain antibiotics, anti-inflammatories or the herbal supplement St. John's Wort
  • You have an eye condition that makes your eyes vulnerable to light damage

Ultraviolet light

Light therapy boxes should be designed to filter out harmful ultraviolet (UV) light, but some may not filter it all out. UV light can cause skin and eye damage. Look for a light therapy box that emits as little UV light as possible. If you have concerns about light therapy and your skin, talk to your dermatologist.

Tanning beds: Not an alternative

Some people claim that tanning beds help ease seasonal affective disorder symptoms. But this hasn't been proved to work. The UV light released by tanning beds can damage your skin and greatly increase your risk of skin cancer.

Caution for bipolar disorder

Light therapy may trigger mania in some people with bipolar disorder, so get advice from your doctor before starting light therapy. If you have any concerns about how light therapy may be affecting your mood or thoughts, seek help right away.

March 19, 2016
  1. AskMayoExpert. Seasonal affective disorder (SAD). Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2015.
  2. Martensson B, et al. Bright white light therapy in depression: A critical review of the evidence. Journal of Affective Disorders. 2015;182:1.
  3. Lam RW, et al. Efficacy of bright light treatment, fluoxetine, and the combination in patients with nonseasonal major depressive disorder: A randomized clinical trial. JAMA Psychiatry. 2016;73:56.
  4. Racz E, et al. Phototherapy and photochemotherapy for psoriasis. Dermatologic Clinics. 2015;33:79.
  5. Van Maanen A, et al. The effects of light therapy on sleep problems: A systematic review and meta-analysis. Sleep Medicine Reviews. 2016;29:52.
  6. Avery D. Seasonal affective disorder: Treatment. http://www.uptodate.com/home. Accessed Feb. 8, 2016.
  7. Sanassi LA. Seasonal affective disorder: Is there light at the end of the tunnel? JAAPA. 2014;27:18.
  8. Melrose S. Seasonal affective disorder: An overview of assessment and treatment approaches. Depression Research and Treatment. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4673349/. Accessed Feb. 8, 2016.
  9. Kurlansik SL, et al. Seasonal affective disorder. American Family Physician. 2012;86:1037.
  10. O'Leary RE, et al. Update on tanning: More risks, fewer benefits. Journal of the American Academy of Dermatology. 2014;70:562.
  11. Seasonal affective disorders (SAD) — Treatment. NHS Choices. http://www.nhs.uk/Conditions/Seasonal-affective-disorder/Pages/Treatment.aspx. Accessed Feb. 15, 2016.
  12. Hall-Flavin DK (expert opinion). Mayo Clinic, Rochester, Minn. Feb. 15, 2016.