Regular nighttime habit could be increasing your risk of heart disease

A common habit may be increasing your risk of heart disease, heart failure and stroke, a study suggests. Researchers found that people who were exposed to light at nighttime — for example, from TVs, phone and laptops — had higher risk of cardiovascular disease and other heart problems.

The study included data from almost 89,000 Brits who wore wrist sensors to measure their light exposure. They health was then tracked using their medical records for nearly 10 years. Those with the highest exposure to light at night were 23-32% higher risk of developing coronary artery disease and 42-47% higher risk of suffering a heart attack.

They were also 28-32% more likely to suffer from an irregular heartbeat and 28-30% more likely to have a stroke, compared to those who experienced darker conditions.

The researchers noted that the links between higher night light exposure and heart failure of coronary artery disease were stronger for women, while the links with heart failure and irregular heartbeat were stronger for younger people.

Writing in a preprint published on the medRxiv server, they concluded: “Night light exposure was a significant risk factor for developing cardiovascular diseases in this cohort.

“In addition to current preventative measures, avoiding light at night may be a useful strategy for reducing risks of cardiovascular diseases.”

Light at night is known to disrupt the circadian rhythm — the body’s natural internal process that regulates the sleep-wake cycle.

Previous studies have similarly shown that people who experience more disruption, such as shift workers, are more likely to suffer from heart problems.

The research, which analysed 13 million hours of light exposure data, also found that people who were exposed to brighter light during the day has lower risks of coronary heart disease, heart failure and stroke.

The experts said their study was the first to establish night light as an important risk factor by looking at patterns of personal exposure and heart diseases.

They added: “Cardiovascular diseases are the leading cause of global morbidity and mortality. Current behavioural recommendations for preventing cardiovascular diseases include maintaining a healthy diet, attaining adequate physical activity, and avoiding alcohol and tobacco.

“Our findings demonstrate that, in addition to current recommendations, avoiding night light may be a promising approach for preventing cardiovascular diseases."