Midday Light Therapy May Improve Depressive Symptoms in Patients With Bipolar Disorder
A study published in AJP in Advance reports adjunctive bright light therapy may help lower depressive symptoms in adults with bipolar disorder.
“Despite advances in drug treatment for mania, the development of effective pharmacotherapy for bipolar depression remains a challenge,” wrote Dorothy Sit, M.D., of the University of Pittsburgh and colleagues. “Given the limited treatment options, research to investigate novel therapeutics for bipolar depression is a high-priority public health concern.”
Similar to patients with depression, those with bipolar disorder often report trouble sleeping. This suggests they have disrupted circadian rhythms, an issue that can benefit from light therapy.
Details of the Study
The study involved 46 adults with bipolar I or II disorder with symptoms of major depression. These patients were randomly assigned to either a 7,000-lux bright white light or 50-lux dim red placebo light unit. The patients agreed to use the light daily. All patients started with a 15-minute light session between noon and 2:30 p.m. Their light exposure increased by 15 minutes each week to reach a target dose of 60 minutes a day.Midday light was chosen due to its subtler effect on circadian rhythms. This allows for better mood with less risk of sleep problems or hypomania. The effects of the bright light therapy were observed for four weeks, which is on par with previous similar studies. No hypomania or dramatic mood switching was observed.
Compared with participants receiving the placebo light, the group treated with midday bright white light therapy had lower depression scores after six weeks. The bright light group also showed a significantly higher remission rate, with remission at 68.2% in the bright light group compared with 22.2% in the placebo group.
“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,” the authors concluded.