Health / Wellness

Irregular Sleep Schedules Linked to Higher Heart Event Risk

More than a million nights of tracker data say the clock matters, not just the hours: shifting bedtimes tracked with more heart attacks, strokes and heart failure.

Sloane MercerAI editorial voice · 1 min read

The analysis was built from wrist-worn trackers worn by 10,362 adults in the NIH's All of Us research program. (Tyler Hendy, CC0)

Summary

An analysis of more than one million tracked nights linked irregular sleep timing to a 20% to 23% higher risk of serious heart events.

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Adults whose sleep timing shifted night to night faced a 20% to 23% higher risk of serious heart events, researchers reported. [Is a consistent sleep schedule important to heart health? — Medical Xpress, reporting American Heart Association research]

The preliminary analysis, presented at the American Heart Association's Scientific Sessions 2026 in Chicago, rebuilt more than one million nights from 10,362 adults in the NIH's All of Us program. None had heart or metabolic disease when tracking began. [Is a consistent sleep schedule important to heart health? — Medical Xpress, reporting American Heart Association research] [Sleep regularity predicts cardiometabolic disease risk — The Cardiology Advisor]

Regularity, not just duration, carried the signal. 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, a 29% higher risk of cardiomyopathy and a 20% higher risk of heart failure. Completing more 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. [Is a consistent sleep schedule important to heart health? — Medical Xpress, reporting American Heart Association research] [Sleep regularity predicts cardiometabolic disease risk — The Cardiology Advisor]

Sleep was characterized over a roughly six-month baseline window from the trackers, and participants were followed for a median of 3.7 years. The average participant was 53, and about 69% were women. 'Having a regular sleep schedule — consistent bedtimes, wake times and sleep duration from night to night — is a practical, actionable step anyone can take,' said lead researcher Nguyen Minh Tuan Viet of Boston Children's Hospital and Harvard Medical School. [Is a consistent sleep schedule important to heart health? — Medical Xpress, reporting American Heart Association research]

The study is observational and preliminary, so it can't establish cause and effect, and sleep stages came from wrist trackers worn at home rather than from lab monitoring. Marie-Pierre St-Onge of Columbia, who chaired the AHA's 2025 sleep statement and wasn't involved, urged the same caution: the data support studying regularity further, not yet prescribing it with the confidence behind sleep duration. What's controllable is the schedule itself — the same bedtime and wake time, weekends included. [Is a consistent sleep schedule important to heart health? — Medical Xpress, reporting American Heart Association research]

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