Exposure to light during sleep may alter heart structure and function

Arabia.net – A scientific study involving more than 10,000 adults found that exposure to light during sleep, even at low levels, is associated with subtle changes in the heart’s structure and function.

The study, published in the European Heart Journal, relied on data from participants in the UK Biobank. The results showed that individuals exposed to higher levels of nighttime light were more likely to exhibit signs of “cardiac remodeling,” a term for structural and functional changes in the heart that can occur in response to chronic stress or cardiac injury.

Participants who were exposed to nighttime light for longer periods had heart walls that were approximately 1.5 percent thicker compared with those who slept in near darkness. Their left ventricular mass was about 2.4 percent higher, while cardiac contraction efficiency was roughly 1.9 percent lower.

The study also found a 29 percent increased risk of heart failure, a 15 percent increased risk of atrial fibrillation, a 24 percent increased risk of myocardial infarction, a 33 percent increased risk of stroke, and a 26 percent increased risk of death from cardiovascular disease.

Researchers noted that shorter sleep duration may be one factor explaining the link between nighttime light and cardiac changes, accounting for between 25 and 50 percent of the changes observed in the study.

They suggest that nighttime light may affect melatonin secretion, the hormone that regulates the sleep-wake cycle, potentially leading to sleep disturbances and increased strain on the heart.

The researchers indicate that reducing light sources in the bedroom, such as using blackout curtains or an eye mask, may be a simple measure to improve sleep conditions. However, the mechanisms linking nighttime light to heart health require further direct research.