Midday Bright Light Therapy Helpful for Bipolar Depression

by | Dec 18, 2017 | 2017, Brain Health, Depression

Written by Angeline A. De Leon, Staff Writer. Four weeks of 15-minute daily sessions of 7000-lux white light significantly improved symptoms of depression in participating subjects with bipolar disorder.

depressionDespite advances in the understanding of mood disorders, bipolar disorder, involving recurrent episodes of mania and depression, remains one of the most difficult to treat. Patients with the disorder are particularly vulnerable to environmental factors such as light, which may modify biological circadian rhythms and potentially induce relapse 1. Depressed bipolar patients, for example, are known to demonstrate delayed sleep phases and erratic sleep/wake cycles 2. Research suggests that exposure to bright light, even if artificial (known as light therapy), can affect levels of brain chemicals like serotonin, which are critically involved in mood regulation 3. Pilot studies, for example, find that midday or evening bright light therapy produces the same antidepressant effects in patients with seasonal depression as standard medication 2, even improving overall quality of sleep in healthy subjects and older patients with insomnia 4,5. Building upon evidence for the therapeutic benefits associated with alterations in circadian rhythm 6, researchers at Northwestern University (2017) investigated the potential for bright light therapy at midday to improve remission rate and symptom level of bipolar depression.

In a randomized, double-blind, placebo-controlled trial, a total of 46 depressed patients (aged 18-75 years) with confirmed bipolar I or II disorder (based on the Structured Clinical Interview for DSM-IV Axis I Disorders) were enrolled. Subjects were randomized to receive treatment with either bright light therapy involving 7,000-lux white light or placebo involving 50-lux dim red light. Sessions began with 15-minute periods of light exposure (between 12:00 pm and 2:30 pm) and after each visit, duration was increased by 15 minutes to reach a target dose of 60 minutes of daily light therapy by Week 4 (or until remission). On a weekly basis, symptoms were evaluated using the Structured Interview Guide for the Hamilton Depression Scale with Atypical Depression Supplement (SIGH-ADS), the Mania Rating Scale, and the Pittsburgh Sleep Quality Index.

After six weeks of bright light therapy, 68.2% of patients experienced remission based on SIGH-ADS scores, compared with 22.2% in the placebo group (adjusted Odds Ratio = 12.64, 95% Confidence Interval: 2.16-74.08, p = 0.004). Patients receiving bright light therapy also demonstrated lower mean depression scores at the end of the study period (9.18 +/- 6.6 vs. 14.94 +/- 9.2, adjusted β = -5.91, p = 0.023). Sleep quality scores improved with both treatments, however, no significant between-group differences were reported. No hypomania or mood polarity switches were observed.

Overall, data from the trial support the potential of midday bright light therapy as an adjunctive treatment for symptoms of bipolar depression. Daily exposure to bright light for several weeks was proven to effectively induce robust antidepressant effects, potentially even mitigating risk of hypomania and mixed symptoms. It remains for future studies, however, to outline the precise biological mechanisms involved in treatment response. 

Source: Sit DK, McGowan J, Wiltrout C, et al. Adjunctive bright light therapy for bipolar depression: a randomized double-blind placebo-controlled trial. Am J Psychiatry. 2017; 10.1176/appi.ajp.2017.16101200.

Posted December 18, 2017.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

References:

  1. Perlis RH, Ostacher MJ, Patel JK, et al. Predictors of recurrence in bipolar disorder: primary outcomes from the Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD). American Journal of Psychiatry. 2006;163(2):217-224.
  2. Terman M, Terman JS, Quitkin FM, McGrath P, Stewart J, Rafferty B. Light therapy for seasonal affective disorder. Neuropsychopharmacology. 1989;2(1):1-22.
  3. Sit D, Wisner KL, Hanusa BH, Stull S, Terman M. Light therapy for bipolar disorder: a case series in women. Bipolar disorders. 2007;9(8):918-927.
  4. Terman JS, Terman M, Lo E-S, Cooper TB. Circadian time of morning light administration and therapeutic response in winter depression. Archives of general psychiatry. 2001;58(1):69-75.
  5. Hashimoto S, Kohsaka M, Nakamura K, Honma H, Honma S, Honma K-i. Midday exposure to bright light changes the circadian organization of plasma melatonin rhythm in humans. Neuroscience letters. 1997;221(2):89-92.
  6. Mishima K, Okawa M, Shimizu T, Hishikawa Y. Diminished melatonin secretion in the elderly caused by insufficient environmental illumination. The Journal of Clinical Endocrinology & Metabolism. 2001;86(1):129-134.