Heart attack risk from irregular sleep revealed

Maintaining a consistent sleep schedule may be an important factor in protecting the heart, according to preliminary results of an independent study to be presented at the American Heart Association (AHA) Scientific Sessions in November 2026. This was reported on the AHA website.

"While we often focus on getting eight hours of sleep each night, a regular sleep schedule — consistent bedtime, wake time, and sleep duration from night to night — is a practical step that may help protect the heart and blood vessels," noted lead researcher Nguyen Minh Tuan Viet, a neuroscientist and postdoctoral fellow at Boston Children's Hospital and Harvard Medical School.

Researchers analyzed sleep data from more than 10,000 adults who wore activity trackers as part of the NIH "All of Us" program. They tracked the amount of sleep, its quality (the proportion of light, deep, and REM stages), regularity (how sleep duration, bedtime, and wake time varied), sleep timing (related to chronotype — the tendency to be a "night owl" (the organization has been included by the Ministry of Justice in the list of foreign agents) or a "morning lark"), as well as the number and duration of completed sleep cycles.

Sleep was assessed over approximately six months, after which participants were followed for an average of 3.7 years.

Variations in sleep timing from night to night over the approximately six-month period were associated with a 20–23% increase in the risk of major cardiac events — heart attack, stroke, and heart failure.

Every 29 minutes of increase in sleep duration variability was associated with a 24% higher risk of a combined cardiovascular outcome, including a 29% higher risk of heart muscle disease and a 20% higher risk of heart failure. Meanwhile, a greater number of complete sleep cycles per night was associated with a 28% reduction in the risk of atrial arrhythmia (a common type of heart rhythm disorder), while an unusually long sleep cycle was associated with a 55% increase in the risk of heart attack or stroke.

"Sleep irregularity is often associated with weekends — on Friday we go to bed a little later; or with shift work. This can be harmful to the heart. Sometimes we cannot control sleep quality. But regularity, maintaining a consistent bedtime throughout the week and waking up at the same time every morning — that is something some people are able to control," summarized Nguyen Minh Tuan Viet.