October 09, 2017
2 min read

Midday bright light therapy improves bipolar depression

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Adjunctive bright light therapy at midday improved remission rate and depression symptoms among adults with bipolar I or II disorder and depression.

“We previously conducted a dose-finding, safety and efficacy pilot study of the effects of light therapy for patients with stable depression in the context of bipolar disorder. Morning light therapy induced full response in one of four patients and, unexpectedly, hypomania in the other three patients,” Dorothy K. Sit, MD, of Feinberg School of Medicine, Northwestern University, Chicago, and colleagues wrote. “Other researchers have been unable to demonstrate any effect of morning light therapy compared with placebo in patients with bipolar depression.”

To assess the efficacy of bright light therapy at midday for remission rate, depression symptom level, and rate of mood polarity switch in bipolar disorder, researchers conducted a randomized double-blind, placebo-controlled trial among adults with bipolar I or II disorder receiving stable dosages of antimanic medication. Study participants were randomly assigned to receive 7,000-lux bright white light (n = 23) or 50-lux dim red placebo light (n = 23).

Symptoms were measured weekly with 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. Researchers defined remission as a SIGH-ADS score of 8 or less.

At baseline, both treatment groups had moderate depression and no hypomanic or manic symptoms, according to results.

At weeks 4 through 6, participants who received the bright white light had significantly higher remission rates (68.2% vs. 22.2%; OR = 12.6) compared with placebo.

At the final visit, participants who received the bright white light had significantly lower depression scores compared with placebo (9.2 vs. 14.9).

Researchers did not find switches in mood polarity.

Sleep quality improved among both treatment groups, with no significant between-group differences.

“The study findings provide evidence that confirms the efficacy of add-on bright light therapy for treatment of bipolar depression. The novel use of a dose-titration protocol, implementation of bright light therapy at midday and the requirement for concurrent antimanic treatment mitigated the risks for emergent mania or hypomania,” the researchers wrote.

“Given its efficacy, ease of use and tolerability, midday light therapy is ideally suited for depressed patients with bipolar disorder, and it may eventually gain widened acceptance with improved practitioner awareness,” they continued. – by Amanda Oldt

Disclosures: The authors report no relevant financial disclosures.