Evening Light Exposure

The study compared 100 Lux light exposure against a control condition of less than 3 Lux. Substantial evening and night light exposure is associated with worse survival outcomes compared to high daytime exposure. Research published in the Proceedings of the National Academy of Sciences examined how nighttime light exposure affects insulin sensitivity in healthy subjects. Exposure to 100 Lux overnight decreased heart rate variability. Exposure to 100 Lux overnight increased heart rate during sleep. The blood pressure effect of nighttime light occurs even through closed eyelids during sleep. Light exposure at night increases blood pressure. Light exposure between midnight and 7:00 AM increases mortality risk. Environments with brighter nights and darker days predict higher mortality rates. Light exposure after 9:00 PM is associated with increased mortality rates. Environmental modifications to eliminate nighttime light are the most practical recommendation for the general population. Minimizing artificial light exposure after 9:00 PM is recommended to reduce mortality risk.