Maintaining a consistent sleep schedule may be an important factor in protecting the heart, according to new preliminary research presented at the American Heart Association’s Scientific Sessions 2026. The study, which analyzed more than 1 million nights of sleep from over 10,000 adults, found that highly irregular bedtimes and varying sleep duration from night to night were linked to a higher risk of heart attack, stroke, heart failure, and other cardiovascular events.
The research, led by Nguyen Minh Tuan Viet, M.D., Ph.D., a neuroscientist and postdoctoral research fellow at Boston Children’s Hospital and Harvard Medical School, used data from the National Institutes of Health’s “All of Us” Research Program. Participants wore activity tracking devices, and researchers characterized their sleep over roughly a six-month baseline window before following them for a median of 3.7 years for cardiovascular events.
“While we often focus on getting a full eight hours of sleep every night, having a regular sleep schedule — consistent bedtimes, wake times, and sleep duration from night to night — is a practical, actionable step anyone can take that may help protect their heart and blood vessels,” Viet said.
The findings showed that changes in sleep timing from night to night were associated with a 20% to 23% higher risk of serious heart events, including heart attack, stroke, and heart failure. Each 29-minute increase in how much a person’s sleep length varied from night to night was associated with a 24% higher risk of the combined cardiovascular outcome, including a 29% higher risk of cardiomyopathy and a 20% higher risk of heart failure. Having a greater number of complete sleep cycles each night was associated with a 28% lower risk of atrial arrhythmia, while an unusually long sleep cycle was linked to a 55% higher risk of heart attack or stroke.
Viet noted that irregular sleep is often due to weekends or shift work. “Sometimes the quality of sleep is something we cannot control. But the regularity, consistent bedtimes throughout the week and waking up at the same time every morning, is something some people can control,” he said.
Marie-Pierre St-Onge, Ph.D., a professor of nutritional medicine at Columbia University Irving Medical Center and chair of the Association’s 2025 scientific statement on Multidimensional Sleep Health: Definitions and Implications for Cardiometabolic Health, cautioned that the study is observational and cannot establish cause and effect. “This study highlights another potential important sleep characteristic to consider for heart health,” St-Onge said. “However, contrary to the years of research showing how insufficient sleep affects cardiovascular risk factors, we are still lacking the data to support a causal, independent impact of sleep regularity on cardiovascular disease risk.”
The study’s limitations include its observational design and the use of wearable devices rather than brain-monitoring equipment in a sleep lab. The findings are considered preliminary until published in a peer-reviewed journal. The research adds to a growing body of evidence linking sleep patterns to cardiovascular health, including previous Association releases on body clocks and sleep duration and quality. The full abstract and the 2026 Online Program Planner are available online. The Association’s financial information is available here.
