A weekend lie-in could increase your risk of stroke, researchers say

An analysis of more than one million nights of sleep has found that varying the time you go to bed could be bad for your heart and increase the risk of strokes.

Experts studying the impact of sleep on heart health also found that varying the length of sleep too much, such as having a long lie-in or skipping going to bed, may also have a negative effect.

The research, which is being presented at the American Heart Association’s Scientific Sessions 2026 in Chicago but is yet to be peer-reviewed, concluded that maintaining a consistent sleep schedule may be an important factor in protecting the heart.

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.”

Researchers analysed sleep data from more than 10,000 adults who wore an activity tracking device as part of the National Institutes of Health’s All of Us research programme.

The study looked at sleep quantity (how many total hours a person slept each night), sleep quality (how much of the night was spent in light, deep and REM sleep), and how long a person was awake after first falling asleep.

Researchers also looked at whether sleep duration, bedtime and wake-up time changed from night to night over around six months, as well as the usual times a person fell asleep and woke up. Any indications for a person’s natural tendency to be a night owl or an early bird were included.

The number of “sleep cycles” completed each night (the interval from the end of one REM period to the end of the next, including the light and deep stages in between) were also examined.

The results showed changes in sleep timing from night to night over about a six-month period were linked to a 20 to 23 per cent higher risk of serious issues, including heart attack, stroke and heart failure.

Every 29-minute increase in how much a person’s sleep length varied from night to night was also linked with a higher risk, including a 29 per cent higher risk of having a disease of the heart muscle, which leaves the heart unable to pump enough blood through the body, and a 20 per cent higher risk of heart failure.

Having a greater number of complete “sleep cycles” each night led to a 28 per cent lower risk of atrial arrhythmia, a common type of irregular heartbeat.

In contrast, an unusually long sleep cycle was linked to a 55 per cent 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.”

People in the study had an average age of 53, and about seven in 10 were women. None had heart or metabolic disease at the start of the study.

Sleep was tracked for around six months and then people were followed for almost four years to see if they suffered heart issues.