Maintaining a consistent sleep schedule may be an important factor in protecting heart health, according to 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 inconsistent bedtimes or varying sleep duration from night to night was linked to a higher risk of heart attack, stroke, heart failure, and other cardiovascular events.
Researchers used data from the National Institutes of Health's "All of Us" Research Program, where participants wore activity tracking devices. They examined multiple dimensions of sleep, including quantity, quality, regularity, timing, and cycles. The analysis revealed that changes in sleep timing from night to night over about a six-month period 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 linked to a 24% higher risk of the combined cardiovascular outcome.
"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," said lead researcher Nguyen Minh Tuan Viet, M.D., Ph.D., a neuroscientist and postdoctoral research fellow at Boston Children's Hospital and Harvard Medical School. Viet noted that irregular sleep was linked to a wider range of heart conditions than expected. "Sleep irregularity is often due to weekends - we get to sleep a little bit later on a Friday night; or people have shift work. This may not be good for your heart health," he said. "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."
The findings should be interpreted cautiously, said American Heart Association volunteer expert Marie-Pierre St-Onge, Ph.D., C.C.S.H., FAHA, who chaired the Association's 2025 scientific statement, Multidimensional Sleep Health: Definitions and Implications for Cardiometabolic Health, and was not involved in the study. "This study highlights another potential important sleep characteristic to consider for heart health, which adds to the body of research we currently have on sleep duration," 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. This study should prompt scientists to further evaluate links between sleep regularity and cardiovascular disease, so that we can make the same recommendations for regularity that we can for duration."
The study followed participants for a median of 3.7 years and adjusted for multiple factors, including age, sex, race, education, income, smoking, alcohol use, cancer, and mental health conditions. As an observational study, it could not establish cause and effect, and sleep stages were measured with wearable devices rather than 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 on sleep and heart health, including previous American Heart Association releases such as Body clocks matter for heart health and Sleep matters: duration, timing, quality and more may affect cardiovascular disease risk. In 2022, the Association added sleep to its cardiovascular health checklist, as noted in American Heart Association adds sleep to cardiovascular health checklist.
For those concerned about heart health, the study suggests that keeping consistent bedtimes and wake times could be a simple, low-cost addition to traditional risk-reduction strategies. The research was presented at Scientific Sessions 2026, a premier global exchange of cardiovascular science. More information is available at heart.org and stroke.org.
