Preventive effect of morning light exposure on relapse into depressive episode in bipolar disorder.

Abstract

OBJECTIVE:

Light therapy has been suggested to have a curative effect on bipolar depression; however, preventive effects of light exposure on depressive episodes remain unclear. This study evaluated whether daytime light exposure in real-life situations was associated with a preventive effect on relapse into depressive episodes in patients with bipolar disorder.

METHODS:

This prospective, naturalistic, observational study was conducted in Japan between August 2017 and June 2020. Outpatients with bipolar disorder were objectively evaluated for daytime light exposure over 7 consecutive days using an actigraph that could measure ambient light at baseline assessment and then assessed at 12-month follow-up for relapse into mood episodes.

RESULTS:

Of 202 participants, 198 (98%) completed follow-up at 12 months and 78 (38%) experienced relapse into depressive episodes during follow-up. In a Cox proportional hazards model adjusting for potential confounders, a longer time above 1000 lux at daytime was significantly associated with decrease in relapse into depressive episodes (per log min; hazard ratio, 0.66; 95% confidence interval, 0.50-0.91). In addition, a higher average illuminance and longer time above 1000 lux in the morning exhibited a significant decrease in relapse into depressive episodes (per log lux and per log min; hazard ratio, 0.65 and 0.61; 95% confidence interval, 0.49-0.86 and 0.47-0.78, respectively). The association between daytime light exposure and relapse into manic/hypomanic/mixed episodes was not significantly different.

CONCLUSION:

A significant association was observed between increased daytime light exposure, mainly in the morning, and decreased relapse into depressive episodes.

• Authors: Yuichi Esaki, Kenji Obayashi, Keigo Saeki, Kiyoshi Fujita, Nakao Iwata, Tsuyoshi Kitajima
• Journal: Acta psychiatrica Scandinavica (Acta Psychiatr Scand) Vol. 143 Issue 4 Pg. 328-338 (04 2021) ISSN: 1600-0447 [Electronic] United States
• PMID: 33587769 (Publication Type: Journal Article, Observational Study, Research Support, Non-U.S. Gov't)
• Copyright: © 2021 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Topics

• Bipolar Disorder (prevention & control)
• Chronic Disease
• Depression (prevention & control)
• Humans
• Japan
• Light
• Proportional Hazards Models
• Prospective Studies
• Recurrence
• Time Factors