What the AHA released
The abstract (MDP2618) is described in the AHA news release "Is a consistent sleep schedule important to heart health?". Researchers led by Nguyen Minh Tuan Viet (Boston Children's Hospital and Harvard Medical School) combined more than 1 million nights of sleep from 10,362 adults in the National Institutes of Health's All of Us Research Program. Participants averaged 53 years of age, about 69% were women, and none had heart or metabolic disease at the start.
Sleep was characterised over a baseline window of roughly six months. The team then followed participants for a median of 3.7 years and adjusted the analysis for age, sex, race, education, income, smoking, alcohol use, cancer and mental health conditions.
Key findings in numbers
- Night-to-night changes in sleep timing were linked to a 20–23% higher risk of serious heart events, including heart attack, stroke and heart failure.
- Each 29-minute increase in how much 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 heart muscle disease and a 20% higher risk of heart failure.
- More complete sleep cycles per night were associated with a 28% lower risk of atrial arrhythmia.
- An unusually long sleep cycle was linked to a 55% higher risk of heart attack or stroke.
The lead author named weekends and shift work as the usual sources of irregular sleep. Marie-Pierre St-Onge of Columbia University, who chaired the AHA's 2025 scientific statement on multidimensional sleep health and was not involved in the study, said the findings should be interpreted cautiously, because data is still lacking to support a causal, independent effect of sleep regularity on cardiovascular disease. She added that stable sleep schedules can help people reach a better sleep duration.
Two limits matter for anyone reading their own data. The study is observational, so it shows association, and sleep stages came from wearables at home rather than from the brain-monitoring equipment of a sleep lab, the standard method for sleep studies. Abstracts at AHA meetings are not peer-reviewed and stay preliminary until a full paper is published.
Regular and irregular weeks look different in your data
A weekly average can hide very different weeks. The chart shows two illustrative weeks: one with bedtimes inside a 30-minute window, one with a late weekend.
How to check your own sleep regularity
Oura, WHOOP, Garmin and Apple Watch record bedtime, wake time and total sleep for every night. Four steps turn those raw fields into a regularity check:
- Export or sync at least four weeks of nights from one device, so weekends appear several times.
- For each night, note bedtime, wake time and total sleep. Mark work days, weekends, travel and shift nights.
- Compare the spread: how far bedtime and sleep length move from your own typical night, and on which days. The AHA study looked at both of these variations.
- If weekends drive the spread, test one change for two to three weeks, for example the same wake time seven days a week, and compare against your baseline. Our consistent bedtime experiment lays out the protocol.
| Field in your wearable | What the AHA study looked at | What to watch |
|---|---|---|
| Bedtime and wake time | Night-to-night changes in sleep timing | Weekend shifts and late nights after work events |
| Total sleep | Variation in sleep length; each extra 29 minutes of spread carried 24% higher combined risk | Short nights followed by long catch-up nights |
| Sleep stages | Number and length of sleep cycles | Read as a rough trend: the study measured stages with home wearables, without sleep-lab brain monitoring |
A regular schedule also shows up in other signals. Our guide on sleep consistency and HRV explains how to read overnight HRV next to bedtime, and sleep tracking beyond stages covers which sleep numbers hold up.
See your sleep spread against your own baseline
Longvai connects Oura, WHOOP, Garmin and Apple Health or a CSV upload, builds a personal control chart for each metric and flags drift beyond 2–3 standard deviations of your own range. See how this works for sleep and recovery tracking; the free plan covers up to 2 sources.
What this means for your own data
The finding adds sleep regularity to sleep duration as a pattern worth watching. It gives no threshold for your bedtime spread and no proof that fixing it lowers risk. Use the numbers to see your own pattern, run a time-limited change, and keep decisions about heart risk, chest pain, palpitations or a diagnosed sleep disorder with your doctor. Longvai is not a medical device.
FAQ
Is sleep regularity linked to heart health?
In the AHA 2026 abstract, adults whose sleep timing and length varied more from night to night had a higher risk of heart attack, stroke and heart failure over a median of 3.7 years. The study is observational and preliminary, so it shows an association.
How many people and nights were analysed?
More than 1 million nights from 10,362 adults in the NIH All of Us Research Program, average age 53, with no heart or metabolic disease at the start.
Can my Oura, WHOOP or Apple Watch measure sleep regularity?
They record bedtime, wake time and total sleep for each night. Comparing those fields across four or more weeks shows how much your timing and length move. Stage data comes from the wearable itself, without the brain monitoring used in a sleep lab.
What is a simple first step?
The lead researcher pointed to consistent bedtimes through the week and the same wake time every morning. Try one change for two to three weeks and compare with your baseline.
Turn a month of nights into an answer you can check
Free plan: up to 2 sources. Pro adds the Experiment Tracker for 2–6 week n=1 trials and starts with a 14-day trial.