Simple Sleep Mistake That Could Raise Heart Disease Risk

According to a report by TheSun (UK) on Thursday, January 15, 2026, scientists have warned that sleeping with lights on at night may significantly increase the risk of heart disease. Falling asleep with the TV on, using bright night lights, or being exposed to light while sleeping can disrupt the body’s natural sleep–wake cycle, known as the circadian rhythm, which is important for overall heart health.

Researchers from the United States and Australia studied nearly 90,000 people by tracking their night-time light exposure with wrist-worn sensors. The participants were followed for almost ten years, during which researchers compared light exposure during sleep with later diagnoses of heart-related conditions.

The study found that people exposed to brighter light at night were more likely to develop several serious cardiovascular problems, including heart failure, heart attacks, coronary artery disease, atrial fibrillation and stroke. Those with the highest exposure to light while sleeping were about 56 per cent more likely to develop heart failure and nearly 50 per cent more likely to suffer a heart attack compared with people who slept in darkness.

Importantly, the increased risk was seen regardless of how long participants slept or how good their sleep quality was. Women with high night-time light exposure were found to have a higher risk of coronary artery disease than men.

Experts involved in the research explained that constant exposure to light at night can confuse the body’s internal clock, leading to long-term strain on the heart and blood vessels. They advised keeping bedrooms as dark as possible, noting that avoiding light at night has no real downside. If some light is needed for safety, very dim lighting is recommended, as it has minimal impact on the body’s circadian rhythm.

The researchers concluded that reducing light exposure at night could be a simple and effective step toward lowering the risk of heart disease, especially for people who already have sleep problems or are at higher risk of cardiovascular conditions.