Day and night light exposure are associated with psychiatric disorders

Originally published by Nature Mental Health, 9 October 2023

Circadian rhythm disturbance is a common feature of many psychiatric disorders. 

Light is the primary input to the circadian clock, with daytime light strengthening rhythms and night-time light disrupting them. Therefore, habitual light exposure may represent an environmental risk factor for susceptibility to psychiatric disorders.

This study examined the independent association of day and night-time light exposure with covariate-adjusted risk for psychiatric disorders and self-harm. Greater night-time light exposure was associated with increased risk for major depressive disorder, generalized anxiety disorder, PTSD, psychosis, bipolar disorder, and self-harm behavior. Independent of night-time light exposure, greater daytime light exposure was associated with reduced risk for major depressive disorder, PTSD, psychosis, and self-harm behavior.

Read the full study.