Nighttime Light Exposure Linked to Higher Mortality Risk

Individuals exposed to light more often during the night may face an increased risk of death. Bright nights and dim days disrupt circadian rhythms, leading to health risks. However, a new study indicates that longer daylight exposure may reduce mortality risk.

Disturbances in the body’s circadian rhythms are connected to the onset of diabetes, metabolic syndrome, and obesity, and are also strongly associated with cardiometabolic conditions like stroke, heart attack, and high blood pressure.

In a study involving 89,000 participants between the ages of 40-69, researchers collected over 13 million hours of light exposure data using wrist sensors over a week. The National Health Service monitored participant mortality over approximately an eight-year period. Using motion data, researchers estimated sleep duration, sleep quality, and midsleep timing, while cardiometabolic mortality covered deaths related to circulatory, endocrine, and metabolic conditions.

The findings revealed that high exposure to light at night increases mortality risk by 21-34%, whereas greater light exposure during the day decreases it by 17-34%. This suggests that disrupted circadian rhythms from increased nighttime light and reduced daylight can lead to negative health outcomes. Daylight appears to strengthen circadian rhythms, helping to guard against the harmful health effects of circadian irregularities.

The findings highlight the importance of keeping the environment dark during late night and early morning hours, when the body’s central circadian clock is most sensitive to light. Protecting light conditions may be particularly crucial for vulnerable individuals, such as those in intensive care or senior facilities.

Minimizing night light exposure and increasing daylight are highly recommended to promote better health and longevity, offering a simple, practical, and affordable approach.

To view the original scientific study click below:
Brighter nights and darker days predict higher mortality risk: A prospective analysis of personal light exposure in >88,000 individuals