When it comes to getting a good night’s rest, both the quantity and quality of your sleep are important. However, emerging research suggests one subtle way that your sleep quality might become compromised without you realizing it—and it could take years off your life. According to new research published in the journal Proceedings of the National Academy of Sciences, being regularly exposed to bright lights at night and low light levels during the day can raise your risk of all-cause mortality by a shocking 34 percent. So, if you tend to keep your bedside light on late into the evening, you might want to rethink your habit.
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Andrew Phillips, PhD, co-senior author of the study and an associate professor at Flinders University, explained that night-time light disrupts circadian rhythms, ultimately leading to adverse cardiometabolic outcomes.
“Disruption to the body’s circadian rhythms is linked to the development of metabolic syndrome, diabetes, and obesity and is also strongly implicated in the development of cardiometabolic diseases including myocardial infarction, stroke, and hypertension,” Phillips said in a news release.
The study included UK Biobank data from 89,000 adult participants, all between the ages of 40 and 69. The researchers analyzed over 13 million hours of data over an eight-year follow-up period, tracking the effects of various light levels using light sensors worn by the subjects.
After adjusting for covariates, the researchers concluded that light exposure at night disrupts circadian rhythms by “shifting the timing (phase-shift) and weakening the signal (amplitude suppression) of the central circadian pacemaker in the hypothalamus,” the part of the brain that controls the endocrine system.
Startlingly enough, those who were exposed to high levels of bright light at night had a 21 to 34 percent increased risk of death. On the other hand, those who were exposed to more light during the day had a 17 to 34 percent reduction in risk of death.
“Our findings clearly show that avoiding night light and seeking daylight may promote optimal health and longevity, and this recommendation is easy, accessible, and cost-effective,” Phillips said in the release.
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Past research on the subject has focused on individuals who routinely spend their waking hours at night, such as shift workers. However, the study authors point out that their findings might be especially relevant for vulnerable populations exposed to night light, such as patients in intensive care settings or elderly residents in senior centers.
“These new insights into the potential adverse impact of light have shown us just how important personal light exposure patterns are for your health,” co-senior author and sleep expert Sean Cain, PhD, also a professor at Flinders University, said in the release.
“These findings demonstrate the importance of maintaining a dark environment across the late night and early morning hours, when the central circadian pacemaker is most sensitive to light, and seeking bright light during the day to enhance circadian rhythms,” Cain and his colleagues wrote in the study.
