Scientists from the American Heart Association (AHA) have warned that disruptions in circadian rhythms — the body’s natural 24-hour cycles — can significantly increase the risk of cardiovascular diseases. The findings were published in the journal Circulation.

The new review shows that a malfunction of the “internal clock” affects blood pressure, blood sugar levels, inflammation, and lipid metabolism, creating conditions for the development of hypertension, stroke, and heart attack.

Circadian rhythms regulate nearly all biological processes — from sleep and body temperature to the functioning of the heart and blood vessels. When a person lives out of sync with these natural cycles — due to night shifts, frequent long-distance travel, chronic sleep deprivation, or constant use of electronic devices at night — the body loses its ability to properly regulate stress and workloads. Scientists emphasize that disruptions in the sleep–wake cycle are especially dangerous: even a few nights of irregular sleep can impair the production of hormones responsible for blood pressure and metabolism.

The researchers note that circadian misalignment is often accompanied by other harmful factors such as stress, a sedentary lifestyle, and overeating. Together, they intensify inflammation and reduce cell sensitivity to insulin, increasing the risk of diabetes and atherosclerosis.

The authors urge medical professionals to consider the “time dimension of health” in the prevention and treatment of cardiovascular disease. They also recommend that people pay attention to sleep hygiene and daily routine consistency: going to bed and waking up at the same time, getting enough daylight exposure, and avoiding bright screens in the evening. Even small adjustments to one’s schedule can help resynchronize the internal clock and reduce cardiovascular strain.

Scientists call circadian rhythms the “fourth dimension of health” — along with nutrition, physical activity, and stress. Understanding their role could change future approaches to heart disease prevention.