Are sleep schedule swings bad for the heart?

Clinical takeaway: When counseling patients about sleep, consider emphasizing consistency as well as duration. Regular bedtimes, wake times, and sleep duration may represent a modifiable behavior associated with lower risks of cardiovascular events.

Sleep recommendations typically focus on total hours slept, but less is known about whether variations in sleep timing and duration independently affect cardiovascular health. New data suggest that irregular sleep patterns may be associated with a broad range of adverse cardiovascular outcomes.

In an analysis of more than 1 million nights of sleep from 10,362 adults participating in the NIH All of Us Research Program, researchers examined multiple dimensions of sleep, including duration, quality, timing, regularity, and sleep cycles. Participants had no cardiovascular or metabolic disease at baseline and were followed for a median of 3.7 years. Findings were presented at the American Heart Association Scientific Sessions 2026 and haven’t yet been peer reviewed.

Night-to-night variability in sleep timing over roughly six months was associated with a 20% to 23% higher risk of major cardiovascular events, including myocardial infarction, stroke, and heart failure. Every 29-minute increase in variability in sleep duration was linked to a 24% higher risk of the composite cardiovascular outcome, including a 29% higher risk of cardiomyopathy and a 20% higher risk of heart failure.

Researchers also found that a greater number of complete sleep cycles each night was associated with a 28% lower risk of atrial arrhythmias, while unusually long sleep cycles were linked to a 55% higher risk of heart attack or stroke.

Because the study was observational, it cannot establish causality. Investigators said the findings support further research into whether improving sleep regularity can reduce cardiovascular risk and whether clinical sleep guidance should emphasize schedule consistency alongside sleep duration.

“While we often focus on getting a full eight hours of sleep every night, having a regular sleep schedule, with 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 author Nguyen Minh Tuan Viet of Boston Children's Hospital and Harvard Medical School.

Source: Viet NMT, et al. (2026 Nov 2) American Heart Association Scientific Sessions 2026, Abstract MDP2618. Sleep Regularity and Cardiovascular Disease Risk: Insights From Over 1 Million Nights of Objective Sleep Monitoring in the All of Us Research Program