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November 30, 2017
by Julia Travers

Can Light Therapy Help People with Bipolar Depression?

November 30, 2017 08:00 by Julia Travers

People who have bipolar disorder experience unusual shifts in mood, energy, sleep and the ability to perform daily tasks. This brain disorder is characterized by “up” or manic episodes and “down” or depressive episodes. The depressive side of bipolar disorder is very difficult to treat, Psychiatrist Ken Duckworth, who is medical director of the National Alliance on Mental Illness, tells NPR. He explains that medications that may regulate the manic phase of bipolar disorder are often not as effective with bipolar depression. But, a new treatment option has just been found to be helpful for bipolar depression: midday bright light therapy.


Bright light therapy involves a patient sitting in front of a light box that gives off light mimicking natural sunshine. This therapy is often used by patients experiencing seasonal affective disorder (SAD). Bright light stimulates cells in the eyes that are connected to the hypothalamus, which plays a role in controlling circadian rhythms (daily cycles of activity, rest and various bodily functions). “Activating the hypothalamus at a certain time every day can restore a normal circadian rhythm and thus banish seasonal symptoms,” says Dr. Michael Craig Miller, senior editor with Harvard Health Publications. Sunshine on human skin may also affect the production of serotonin (a mood-regulating neurotransmitter), as a 2013 report in Innovations in Clinical Neuroscience explores. Bright light therapy is also sometimes used by people struggling with dementia, sleep disorders, jetlag and non-seasonal depression.


A team of researchers from the Feinberg School of Medicine at Northwestern University led by Psychiatrist and Lead Author Dorothy Sit carried out a study exploring whether this treatment could help those with bipolar depression. They focused on the effect of a midday dose of bright light therapy on patients with bipolar I or II disorder. These types of the disorder are generally considered severe and moderate, respectively. The patients were all experiencing depression and no manic symptoms at the time and they were all taking antimanic medication during the study.


This was not the first time Sit explored bright light therapy as a treatment for bipolar depression; in 2007 she studied its efficacy with a group of nine women with the condition. She found in this initial study that the participants were “highly sensitive” to the treatment when it was given in the morning, as it typically is in the case of SAD. The participants were so sensitive to morning treatment that it could cause the “induction of mixed states” or a transfer into a manic phase. A switch to midday light therapy was found less likely to have this effect and more likely to reduce depression. For this reason, the recent study tested the light therapy at midday, specifically between noon and 2:30 p.m.


The 2017 study was a randomized double-blind placebo-controlled trial -- in a double-blind experiment, neither the researchers nor the participants know who receives the placebo. Half of the 46 participants received therapy with a 7,000-lux bright white light and half received the placebo: a 50-lux dimmer red light. All patients spent time in front of the light (about 1 foot away) doing any sedimentary activity they chose, such as reading. The duration of the light therapy increased from 15 to 60 minutes daily during the six-week trial.

The group that received the bright white light therapy experienced a higher depression remission rate, which was measured using depression, mania and sleep scales. Bright light therapy recipients showed 68.2 percent remission, while those receiving the red placebo light experienced 22.2 percent remission. During weeks four through six, the bright light group had much lower depression scores than the placebo group: 9.2 versus 14.9. Participants in both groups had improved sleep quality during the trial and none of them experienced the “polarity switches” or induction of manic phases Sit observed in the first trial that included early morning light therapy.

Sit says the bright light patients “returned to work, they were able to look after things at home, they were functioning back to their normal selves again.” The study’s conclusion states, “The data from this study provide robust evidence that supports the efficacy of midday bright light therapy for bipolar depression.”

Nearly 6 million U.S. adults struggle with bipolar disorder and the extreme shifts in mood and energy can be debilitating and incapacitating. Sit tells NPR she thinks further research is needed to explore and confirm bright light therapy’s efficacy in assisting individuals with bipolar depression and in particular, how it effects sleep patterns and circadian rhythms.


This study, “Adjunctive Bright Light Therapy for Bipolar Depression: A Randomized Double-Blind Placebo-Controlled Trial,” was published in the American Journal of Psychiatry in Oct. 2017.

Other references:


Neighmond, Patti. “Light Therapy Might Help People With Bipolar Depression.” NPR, NPR, 27 Nov. 2017, www.npr.org/sections/health-shots/2017/11/27/561574259/light-therapy-might-help-people-with-bipolar-depression?


Miller, M.D. Michael Craig. “Seasonal Affective Disorder: Bring on the Light.” Harvard Health Blog, 29 Oct. 2015, www.health.harvard.edu/blog/seasonal-affective-disorder-bring-on-the-light-201212215663.


Sansone, Randy A., and Lori A. Sansone. “Sunshine, Serotonin, and Skin: A Partial Explanation for Seasonal Patterns in Psychopathology?” Innovations in Clinical Neuroscience, Matrix Medical Communications, 2013, www.ncbi.nlm.nih.gov/pmc/articles/PMC3779905/.


Sit, D, et al. “Light Therapy for Bipolar Disorder: a Case Series in Women.” Bipolar Disorders., U.S. National Library of Medicine, Dec. 2007, www.ncbi.nlm.nih.gov/pubmed/18076544.