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Nocturnal light exposure and cardiovascular risk

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2026-09-11 23:56 UTC → 2026-09-12 02:37 UTC · added ~~removed~~

Research indicates that exposure to artificial light during the night is a significant risk factor for cardiovascular issues. A study published in JAMA Network Open, which followed approximately 89,000 adults for over nine years, found that light exposure between midnight and 6 a.m. could increase the risk of heart attack or stroke by up to 56%. Experts suggest this occurs because artificial light disrupts the circadian rhythm, triggering stress responses and impairing sleep quality. Detailed findings published in the European Heart Journal, utilizing data from over 11,000 UK Biobank participants, have further quantified the physiological impacts. Researchers from Tulane University used wrist-worn light sensors to monitor exposure, finding that levels above 3 lux—roughly equivalent to moonlight—are associated with cardiac remodeling. Specifically, participants showed a 1.5% increase in left ventricular wall thickness and a 2.4% increase in left ventricular mass, which reduces the internal space of the heart chamber. The study also noted a 1.9% reduction in the heart muscle’s ability to contract properly. Longer-term follow-ups conducted 8 to 10 years after initial measurements indicated more severe consequences, including a 29% higher risk of heart failure, a 24% higher risk of heart attack, and a 33% higher risk of stroke. Researchers noted that while disrupted sleep may account for a portion of these ~~effects, light~~ effects—potentially between 24% and 49% of the association—light exposure remains a significant independent factor. To mitigate these risks, experts suggest that reducing light pollution in bedrooms from sources such as smartphones or digital clocks could be a vital strategy for cardiovascular disease prevention, recommending bedroom illumination remain below 1 lux through methods like blackout curtains.

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