How the body’s internal clocks influence heart health

Circadian rhythms, which are hardwired into nearly every cell of the body, regulate the heart and blood vessels. Disruptions to this rhythm—from shift work, poor sleep, or unhealthy habits—can raise the risk of cardiovascular disease. For example, heart attacks are more likely to occur on Mondays than any other day of the week. That’s because people tend to stay up later than usual and then sleep in the next day. On Monday morning, when they have to wake up early again for work, the change may cause subtle changes in blood pressure, hormone secretion, and metabolism that raise heart attack risk.