Night light exposure ups cardiovascular risk

Individuals exposed to brighter lights at night have increased risks of incident coronary artery disease, myocardial infarction, heart failure, atrial fibrillation, and stroke, according to a study.

Researchers analysed cardiovascular disease (CVD) records across 9.5 years from 88,905 UK Biobank participants (mean age 62.4 years, 56.9 percent female). These participants contributed approximately 13 million hours of light exposure data, collected using wrist-worn light sensors (1 week for each participant) and categorized according to the following percentiles: 0 to 50th, 51st to 70th, 71st to 90th, and 91st to 100th.

Records from the UK National Health Service were used to determine the incidence of coronary artery disease, myocardial infarction, heart failure, atrial fibrillation, and stroke after light tracking.

Relative to participants with dark nights (0–50th percentiles), those with the brightest nights (91st–100th percentiles) had between 28-percent and 56-percent higher risks of developing coronary artery disease (adjusted hazard ratio [aHR], 1.32, 95 percent confidence interval [CI], 1.18–1.46), myocardial infarction (aHR, 1.47, 95 percent CI, 1.26–1.71), heart failure (aHR, 1.56, 95 percent CI, 1.34–1.81), atrial fibrillation (aHR, 1.32, 95 percent CI, 1.18–1.46), and stroke (aHR, 1.28, 95 percent CI, 1.06–1.55).

Bright light exposure at night showed stronger associations with the risks of heart failure (p=0.006) and coronary artery disease (p=0.02) among women, as well as more pronounced associations with the risks of heart failure (p=0.04) and atrial fibrillation (p=0.02) among younger participants.

The findings underscore the potential of avoiding light at night, in addition to current preventive measures, as a useful strategy for reducing CVD risks, the researchers said.