Irregular Sleep Schedules Linked to Higher Heart Risks, Study Finds

Maintaining a consistent sleep schedule may be more important for heart health than previously thought, 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 irregular sleep patterns—varying bedtimes, wake times, and sleep duration—were linked to a significantly 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 examined multiple dimensions of sleep, including quantity, quality, regularity, timing, and cycles. The findings showed 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 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.

"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. He noted that sleep irregularity is often due to weekends or shift work, and that while sleep quality may be beyond our control, regularity is something many people can control.

The study also found that having a greater number of complete sleep cycles each night was associated with a 28% lower risk of atrial arrhythmia, a common type of irregular heartbeat, while an unusually long sleep cycle was linked to a 55% higher risk of heart attack or stroke. Viet emphasized that irregular sleep was linked to a much wider range of heart conditions than expected.

Marie-Pierre St-Onge, Ph.D., C.C.S.H., FAHA, a volunteer expert for the American Heart Association and chair of the Association's 2025 scientific statement on Multidimensional Sleep Health: Definitions and Implications for Cardiometabolic Health, cautioned that the findings should be interpreted carefully. "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," said St-Onge, a professor of nutritional medicine and director of the Center of Excellence for Sleep & Circadian Research at Columbia University Irving Medical Center. "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." She added that the study should prompt scientists to further evaluate links between sleep regularity and cardiovascular disease.

The research analyzed data from 10,362 adults with an average age of 53, none of whom had heart or metabolic disease at the start of the study. Sleep was characterized over a roughly six-month baseline window, and participants were followed for a median of 3.7 years. The analysis 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 as a full manuscript in a peer-reviewed scientific journal. The study abstract is available in the 2026 Online Program Planner. For more information on heart health, visit heart.org and stroke.org. The American Heart Association's Scientific Sessions 2026, held Nov. 6–9 in Chicago, is a premier global exchange of the latest scientific advancements in heart and stroke science. The Association receives more than 85% of its revenue from sources other than corporations, and overall financial information is available here. This story is based on a release distributed via NEWMEDIAWIRE.