Exposure to bright light at night — including the glow from phone screens — could significantly raise the risk of heart failure by 56%, according to a new study led by researchers at Flinders University, Australia. The findings suggest that artificial light at night is not just a sleep disruptor but also a major cardiovascular risk factor, especially among adults aged 40 and above.
The large-scale study, published in the Journal of the American Medical Association (JAMA) Network Open, analysed more than 13 million hours of light exposure data collected from nearly 89,000 participants in the UK. The individuals wore wrist sensors that tracked light exposure continuously over several days and were followed up for more than nine years.
Link Between Nighttime Light and Cardiovascular Diseases
The results revealed a strong correlation between bright nighttime light exposure and an increased risk of several cardiovascular conditions:
*56% higher risk of heart failure
*47% higher risk of heart attack
*32% higher risk of coronary artery disease
*28% higher risk of stroke
The researchers concluded that light exposure at night is a “significant and independent risk factor” for developing cardiovascular diseases among adults over 40.
Disruption of the Body’s Natural Clock
Lead author Daniel Windred, Research Associate at Flinders University, emphasized that this is the first large-scale study to demonstrate a direct and independent link between nighttime light exposure and heart disease risk.
“Disrupting your body’s internal circadian clock by repeatedly exposing yourself to bright light at night, when it would typically be dark, increases the risk of developing serious heart conditions,” Windred explained.
The circadian rhythm, which regulates sleep-wake cycles and various physiological functions, can be disturbed by artificial light exposure. This disruption affects hormonal balance, blood pressure regulation, and metabolic functions — all of which contribute to cardiovascular strain.
Women and Younger Adults More Vulnerable
Interestingly, the study found that women and younger adults were particularly sensitive to the effects of nighttime light. Senior co-author Professor Sean Cain of Flinders University’s College of Medicine and Public Health noted, “Women may be more sensitive to the effects of light disrupting their body clock, which aligns with earlier research. In fact, women exposed to high levels of night light showed similar heart failure risks to men — an unusual finding since women generally have some natural protection against heart disease.”
These observations highlight the differential biological responses to circadian disruption, suggesting the need for gender- and age-specific awareness campaigns.
Simple Lifestyle Changes Can Reduce Risk
The researchers recommend practical steps to limit nighttime light exposure and protect cardiovascular health. Suggested measures include:
*Using blackout curtains to block streetlights or external illumination.
*Dimming indoor lights in the evening.
*Avoiding phone, tablet, and television screens before bedtime.
They noted that these simple behavioral adjustments could significantly reduce the impact of artificial light on heart health.
Reinforcing the Connection Between Light and Heart Health
As reported by thehindu.com, the study adds to growing evidence that modern lighting habits and screen use can have profound effects on physical health beyond sleep disturbances. By shedding light on how our environment interacts with our biology, researchers hope to encourage greater public awareness of circadian health as a crucial aspect of cardiovascular prevention. Professor Cain summarized, “Avoiding bright light at night may be one of the simplest and most effective strategies for protecting the heart.”