Into the Light: Light Therapy and it’s Effect on Improving Mood

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Many forms of depression from major depressive disorder (MDD), bipolar depression, to seasonal affective disorder (SAD) also known as major depressive disorder with seasonal pattern, affect millions of people. Depression is estimated to affect up to 17.3 million people in the United States (National Institute of Mental Health, 2019). Additionally, seasonal affective disorder affects an estimated 10 million Americans (Melrose, 2015). Light therapy (LT) has shown evidence to improve symptoms of different depression types.


Light therapy is commonly associated with the treatment of SAD and is considered a first line treatment for those affected by SAD (Campbell, Miller, & Woesner, 2017). SAD is a type of depression related to seasonal changes. Typically depression begins to worsen during fall and continues to increase into the winter months although it can develop during spring or summer as well. Its proposed that subjecting patients with SAD to bright white light lengthens their photoperiod (the length of time exposed to light in a day) and assists in correcting the circadian phase shift caused by decreased sunlight during winter seasons (Rosenthal et al., 1984). The correction in circadian rhythm and increased photoperiod helps reduce depressive symptoms in several domains. Correcting sleep/wake cycle, decreasing the abundant melatonin production during darker days, assisting the transport of neurotransmitters and increase in vitamin D synthesis all add to LT’s effects on depressive symptoms (Mayo Clinic, 2017). Recommended therapy is use of a fluorescent light box with an intensity of 10,000 lux for 30 min typically in the morning (Praschak-Rieder, & Willeit, 2003). Alternative therapies exist consisting of using an intensity of 2,500 lux for 1-2 hours and varying the time of day as well as using dawn simulation by gradually increasing the bedside light in the AM after waking (Praschak-Rieder & Willeit, 2003). Although LT is considered a first line treatment for SAD, evidence is emerging for its efficacy in other depressive disorders as well.

Who Can it Help?

  • Patients with sleep difficulties

  • Patients with high medication side effect burden

  • Use for other psychiatric disorders

  • Use for patients in higher altitudes

  • Use for night shift workers


The literature shows evidence for light therapy’s use in SAD, nonseasonal major depressive disorder, and adjunctive therapy for bipolar depression. Research has compared LT to cognitive behavioral therapy for SAD (CBT-SAD), LT by itself, LT in combination with an antidepressant and as adjunct to bipolar management with medications.

Light therapy was effective for depression across all articles I reviewed, albiet limited in quantity. LT was comparable to CBT-SAD with an antidepressant for symptom remission of depression although LT for certain symptoms led to faster remission rates than CBT-SAD. LT also had more consistent effects on depression when using LT in combination with an antidepressant (Meyerhoff, Young, & Rohan, 2018), (Lam et al., 2016). LT was also efficacious in the treatment of bipolar depression with higher remission rates and lower depression scores than placebo when managed with medication (Sit et al., 2017).

LT consisted of morning bright light therapy using a light box in the morning with 10,000 lux and a ultraviolet filter for 30-90 min a day for SAD and nonseasonal depression though dosages were increased or decreased based on lack of response or side effects (Meyerhoff, Young, & Rohan, 2018), (Lam et al., 2016). For bipolar depression participants were instructed to use the light box at 7,000 lux with a target dose of 60 minutes during midday as previous studies have showed efficacy of midday or evening LT for bipolar depression (Sit et al., 2017). Across all studies LT showed significant reduction in depressive symptoms as well as achieving remission, with LT achieving symptom relief faster than any other methodology in which it was compared (Meyerhoff, Young, & Rohan, 2018), (Lam et al., 2016), (Sit et al., 2017). Additionally, LT shows efficacy for depressive symptoms with high tolerability, with side effects usually subsiding and not significantly different in rate of occurrences from placebo (Sit et al., 2017), (Lam et al., 2016).



As presented previously, LT has evidence for its efficacy in several depressive disorders. Although antidepressant medication is first line therapy, LT has shown to be as effective as certain antidepressants such as selective serotonin reuptake inhibitors (SSRIs) and even more consistent in conjunction with SSRIs (Lam et al., 2016). With the ease of use and minimal side effect profile, LT can be adopted for patients suffering from depression that may not be responding to current medication management. Evidence also suggests LT may be beneficial for special populations who may prefer non-pharmacological treatment such as children and pregnant women (Sit et al., 2017).

For patients who live in higher altitudes and experience seasonal shifts in their depression, they can benefit from LT during different seasons as their exposure to natural light decreases as daylight becomes shorter (Meyerhoff, Young, & Rohan, 2018), (Rosenthal et al., 1984). Additionally, patients with depression who suffer from sleep difficulties, may benefit from the correction of their circadian rhythm and increase in the transport of certain chemicals in the body from LT, which assist in the decrease of depressive symptoms (Rosenthal et al., 1984).

Although all the existing evidence about light therapy were not synthesized for this article, evidence exists that supports the use of light therapy for those who may need or want alternatives to medication or an additional modality to add to their current medication regimen. Such populations referred to previously include children, pregnant women, elderly patients, those who can not tolerate medications or prefer not to take medications, and those who benefit from medications but may need additional methods to decrease depressive symptoms. Additional populations have research demonstrating efficacy of LT such as those with eating disorders as typical binge episodes have been observed to increase during the fall and winter seasons (Praschak-Rieder, & Willeit, 2003). Adult ADHD has limited but promising evidence as well which show efficacy for LT (Praschak-Rieder, & Willeit, 2003).

Applications for Light Therapy

  • First line treatment for SAD

  • May be used as adjunct therapy for non-seasonal depression

  • May be used as adjunct therapy for bipolar depression

  • Use for pregnant women, elderly or children or those not wanting medication


Although LT has shown efficacy for depressive disorders, limitations may deter its use. Instruction and education on proper set up of the light box, dosage, time of day, time of exposure, angle of the box to the patient’s eyes all need to be considered when being prescribed LT (Praschak-Rieder, & Willeit, 2003). Additionally, consideration for cost and insurance coverage will need to be considered as well. Although an increasing number of private insurers consider LT with a light box appropriate for SAD, some state Medicaid still do not provide coverage (Praschak-Rieder, & Willeit, 2003). For those patients who cannot receive insurance coverage, typically can purchase a light box for approximately $150 (Praschak-Rieder, & Willeit, 2003). Special populations such as pregnant women and medication resistant patients need more research in the area of LT. Additionally, as mentioned previously, further research is needed to establish efficacy of maintenance LT treatments to prevent recurrence of depressive symptoms.


  • Research compared LT to CBT-SAD, LT monotherapy, LT in combination with an antidepressant and as adjunct to bipolar management with medications.

  • Light therapy was effective for depression across all articles.

  • LT was comparable to CBT-SAD and antidepressant for symptom remission

  • LT was effective in bipolar depression


Campbell, P., Miller, A., & Woesner, M. (2017). Bright Light Therapy: Seasonal Affective Disorder and Beyond. The Einstein Journal of Biology and Medicine,32, 13-25

Lieverse, R., Nielen, M. M., Veltman, D. J., Uitdehaag, B. M., Someren, E. J., Smit, J. H., & Hoogendijk, W. J. (2008). Bright light in elderly subjects with nonseasonal major depressive disorder: A double blind randomised clinical trial using early morning bright blue light comparing dim red light treatment. Trials,9(1). doi:10.1186/1745-6215-9-48

Mayo Clinic. (2017, October 25). Seasonal affective disorder (SAD). Retrieved from https://www.mayoclinic.org/diseases-conditions/seasonal-affective-disorder/symptoms-causes/syc-20364651

Melrose, S. (2015). Seasonal Affective Disorder: An Overview of Assessment and Treatment Approaches. Depression Research and Treatment,2015, 1-6. doi:10.1155/2015/178564

Meyerhoff, J., Young, M. A., & Rohan, K. J. (2018). Patterns of depressive symptom remission during the treatment of seasonal affective disorder with cognitive-behavioral therapy or light therapy. Depression and Anxiety,35(5), 457-467. doi:10.1002/da.22739

National Institute of Mental Health. (2019). Major Depression. Retrieved from https://www.nimh.nih.gov/health/statistics/major-depression.shtml

Praschak-Rieder, N., & Willeit, M. (2003). Treatment of Seasonal Affective Disorders. Dialogues in Clinical Neuroscience,5(4), 389-398.

Psychology Today. (2019, February 07). Seasonal Affective Disorder. Retrieved from https://www.psychologytoday.com/us/conditions/seasonal-affective-disorder

Rosenthal, N. E. (1984). Seasonal Affective Disorder. Archives of General Psychiatry,41(1), 72. doi:10.1001/archpsyc.1984.01790120076010

Sit, D. K., Mcgowan, J., Wiltrout, C., Diler, R. S., Dills, J. (., Luther, J., . . . Wisner, K. L. (2018). Adjunctive Bright Light Therapy for Bipolar Depression: A Randomized Double-Blind Placebo-Controlled Trial. American Journal of Psychiatry,175(2), 131-139. doi:10.1176/appi.ajp.2017.16101200

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