Influence of the modern light environment on mood

Exposure to light at night may disrupt circadian organization and is associated with increased rates of major depression.

• Humans and other organisms have adapted to a natural 24-hour solar cycle for their biological processes.
• Widespread adoption of electric light over the past 130 years has altered the timing of light exposure.
• Light is detected by the retina, which sends signals to both the circadian system and areas of the brain related to mood.
• There is a notable increase in major depression rates that parallels rising nighttime light exposure.
• Strong evidence links circadian disruption to mood disorders, with emerging research suggesting nighttime light exposure may also negatively affect mood.

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