Prime Snippets: – Study Finds Overexposure To Light At Night Ups CVD Risk

Blood Pressure device

Study Finds Overexposure to Light at Night Raises CVD Risk

Exposure to light at night may significantly increase the risk of cardiovascular disease (CVD), especially in adults over the age of 50. A large international cohort study suggests that reducing light exposure at night could help lower cardiovascular risk.

Researchers analysed data from 88,905 adults with an average age of 62.4 years. Women made up 56.9% of the study population. The participants came from the UK Biobank, a long-term health database that enrolled around 502,000 people between 2006 and 2010.

As part of the study, 103,669 participants wore light-tracking devices on their dominant wrist for one week between 2013 and 2016. The researchers followed cardiovascular outcomes through November 2022.

Measuring Night-Time Light Exposure

The wrist sensors recorded more than 13 million hours of light exposure. Researchers divided the data into four exposure groups, ranging from the lowest 50% to the highest 10% of night-time light exposure.

They also tracked over 700,000 person-years of follow-up data. The team adjusted their analysis for many known cardiovascular risk factors. These included physical activity, smoking, alcohol intake, diet, sleep duration, diabetes, socioeconomic status, genetic risk, ethnicity, and shift work.

Heart made of glass

Why This Study Stands Out

Most previous studies relied on satellite data to estimate night-time light exposure. Satellite images cannot accurately measure how much light reaches individuals indoors.

This study used personal light sensors, allowing researchers to assess light exposure at the individual level. The team confirmed that the increased cardiovascular risk remained even after accounting for sleep duration, sleep quality, physical activity, chronotype, and seasonal daylight changes.

These results suggest that night-time light exposure itself may raise cardiovascular risk, rather than acting only through poor sleep.

Possible Biological Explanations

Scientists still need to determine exactly how night-time light increases cardiovascular risk. One possible explanation involves melatonin, a hormone that regulates sleep and circadian rhythms.

Light exposure near bedtime can delay and suppress melatonin release. This disruption may affect blood pressure, glucose control, inflammation, and other processes linked to heart disease.

Conclusion

This large-scale study adds strong evidence that excessive exposure to light at night increases the risk of cardiovascular disease, especially in older adults. The findings suggest that reducing night-time light exposure may offer a simple and practical way to protect heart health.

While more research is needed to identify the most critical periods for intervention, limiting artificial light at night could become an important strategy for lowering long-term cardiovascular risk. PRIME