Avoiding Night Light Exposure May Be Key to Heart Health, Researchers Say
Sleeping with the lights on could be doing more harm than you think. A new international study has found a strong association between exposure to brighter night-time light and increased risks of several major cardiovascular conditions, including heart attacks and strokes.
The research, conducted by scientists from the Flinders Health and Medical Research Institute in Australia along with collaborators from the UK and the US, examined the personal light exposure patterns of over 88,000 individuals. Their findings, published as a preprint on medRxiv, suggest that reducing light exposure during sleep may significantly lower the risk of heart disease.
The team analyzed about 13 million hours of light exposure using data from wrist-worn sensors worn by participants over one week. They discovered that individuals exposed to higher levels of artificial light at night faced significantly higher risks of developing coronary artery disease, heart failure, atrial fibrillation (irregular heartbeat), myocardial infarction (heart attack), and stroke.
Women and younger participants showed particularly strong associations, especially for heart failure and coronary artery disease.
The study builds on existing knowledge about circadian rhythms — the body’s internal clock — and how disruption to this natural cycle has been linked to metabolic disorders and cardiovascular problems. “Night-time light may interfere with circadian regulation, potentially triggering metabolic and vascular changes that elevate cardiovascular risk,” the researchers noted.
Importantly, the results remained consistent even after accounting for other heart health factors such as physical activity, alcohol use, smoking, diet, socioeconomic status, sleep duration, and genetic risk.
While the study is still awaiting peer review, it adds weight to growing evidence that sleeping in complete darkness is not just a preference but could be vital for long-term cardiovascular health.
Turning off the lights at night might be a simple and effective addition to heart disease prevention strategies.