New Delhi, 24 Oct

Being exposed to bright light at night, including scrolling through one's phone, could be related to a 56 per cent higher risk of heart failure, and can be a significant risk factor for cardiovascular diseases among adults aged 40 and above, according to a new study.

Researchers led by those at Australia's Flinders University analysed more than 13 million hours of light exposure data collected through sensors that nearly 89,000 people in the UK wore on their wrists. The participants were followed up for more than nine years.

Exposure to light at night was also linked with a 47 per cent higher risk of a heart attack, 32 per cent of coronary artery disease and 28 per cent of stroke.

"Night light exposure was a significant risk factor for developing cardiovascular diseases among adults older than 40 years," the authors wrote in the study published in the Journal of the American Medical Association (JAMA) Network Open.

Lead author Daniel Windred, research associate at Flinders University, said, "This is the first large-scale study to show that simply being exposed to light at night is a strong and independent risk factor for heart disease."

"Disrupting your body's internal circadian clock by repeatedly exposing yourself to bright light at night, when it would typically be dark otherwise, will put you at a higher risk of developing dangerous heart issues," Windred said.

The study also found that women and younger people were especially vulnerable to the impact of light exposure at night.

"Women may be more sensitive to the effects of light disrupting their body clock, which supports earlier research findings," senior co-author Sean Cain, professor at Flinders University's College of Medicine and Public Health, said.

"In fact, women exposed to high levels of night light had similar heart failure risks to men, which is unusual because women typically have some natural protection against heart disease," Cain said.

The researchers suggested avoiding light at night may be a useful strategy for reducing the risks of cardiovascular diseases.

Using blackout curtains, dimming lights, and avoiding screens before bed could help address health risks related to being exposed to light at night, they said.