Going to bed at the same time every day could help stave off heart attacks and strokes, research suggests. A study of more than one million nights of sleep data from 10,000 people found sleep regularity was a critical factor for heart health.
Having inconsistent bedtimes or varying sleep duration from night to night was linked to a higher risk of cardiovascular events.
What the study found
Lead researcher Dr Nguyen Minh Tuan Viet, a neuroscientist and postdoctoral research fellow at Boston Children's Hospital and Harvard Medical School in the US, said: "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."
The study used data from people who wore activity tracking devices that captured information on their sleep quantity, quality, timing, regularity and sleep cycles – the interval from the end of one REM period to the end of the next, including the light and deep stages in between.
Analysis showed that people who had the most changes in sleep timing from night to night over a six-month period were around a fifth more likely to suffer serious heart events, including heart attacks, strokes and heart failure. Each 29-minute increase in the variation in a person's sleep length from night to night was associated with a 24% higher risk of problems.
Sleep cycles and heart risk
Having more complete sleep cycles each night was associated with a 28% lower risk of atrial arrhythmia, a common type of irregular heartbeat. An unusually long sleep cycle was linked to a 55% higher risk of heart attack or stroke.
Dr Viet said: "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.
"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 study measured participants' sleep over a period of around six months, then tracked cardiovascular events for an average of 3.7 years. The analysis was adjusted for factors including age, sex, race, education, income, smoking, alcohol use, cancer and mental health conditions.
Expert caution and context
Researchers noted that the study was observational, so it could not prove that the differences in sleep habits caused the difference in risk of heart problems. The findings were presented at the American Heart Association's Scientific Sessions 2026.
The NHS recommends that most healthy adults need seven to nine hours of sleep per night. Signs that you may not be getting enough sleep include finding it hard to wake up or start the day, feeling tired, irritable or sleepy, and finding it hard to focus or cope with everyday tasks.
Dr Marie-Pierre St-Onge, an American Heart Association volunteer expert and professor of nutritional medicine, said the research should be interpreted cautiously. She added: "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.
"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."
Dr St-Onge, who is the director of Columbia University Irving Medical Center's Center of Excellence for Sleep and Circadian Research in New York City, added: "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.
"Sleep duration and regularity often interact in their relation to heart disease risk. This abstract notes an additional tool to consider when working on improving sleep. Adopting stable sleep schedules can be helpful to achieve better sleep duration as well."
