Nighttime Light Exposure Increases Depression Risk by 30%

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Research Finds Nighttime Light Exposure Increases Depression Risk by 30%

Research Finds Nighttime Light Exposure Increases Depression Risk by 30%.

A new study has revealed that exposure to light during nighttime disrupts our internal body clock, increasing the risk of developing mental illnesses, while daytime light exposure reduces this risk.

This discovery provides a simple and effective non-pharmaceutical means to improve mental health.

Research Finds Nighttime Light Exposure Increases Depression Risk by 30%

Our internal body clock, or circadian rhythm, regulates the cycles of alertness and drowsiness by reacting to changes in light in the environment. Although other factors such as exercise, social activities, and temperature also influence circadian rhythms, light remains the most potent factor.

It’s well-known that circadian rhythm disruption is a common feature of many mental disorders. Therefore, it’s not surprising that light exposure is a modifiable environmental risk factor for mental illnesses. To conduct this research, researchers at Monash University led one of the world’s largest studies on the impact of daytime and nighttime light exposure on the risk of mental disorders.

They recruited 86,772 adult participants from a UK biobank and examined their light exposure, sleep patterns, physical activity, and mental health status. They found that people exposed to bright light at night had a 30% higher risk of developing depression, while those exposed to bright light during the day had a 20% lower risk of depression.

Similar patterns were also found in self-harming behaviors, psychotic disorders, bipolar disorder, generalized anxiety disorder, and post-traumatic stress disorder. The results remained consistent when accounting for demographic factors, physical activity, sleep, shift work, living environment, and cardiovascular health.

“Our research findings could have significant societal implications,” said one of the co-authors of the study, Sean Cain. “Once people realize that their light exposure patterns can have a powerful impact on their mental health, they can take some simple measures to optimize their well-being. That means bright light during the day and darkness at night.”

Researchers suggest that modern lifestyles, especially artificial lighting and the light emitted by devices such as smartphones, computers, and television screens, disrupt our internal body clock, challenging the way our brains have evolved to work best under bright daytime light.

“Today’s humans are challenging this biological norm, spending about 90% of their day indoors under artificial lighting, which is too dim during the day and too bright at night compared to the natural light-dark cycle,” Cain explained. “This confuses our bodies and makes us feel uncomfortable.”

The results of this study indicate that avoiding light at night and seeking light during the day may be a simple and effective non-pharmaceutical approach to improving mental health.

The study has been published in the journal “Nature – Mental Health.”