How late nights harm our hearts revealed as 10,000 Americans agree to have sleep tracked for six months

How late nights harm our hearts revealed as 10,000 Americans agree to have sleep tracked for six months Late nights at the weekend appear to increase our risk of heart attacks, strokes and heart failure by over 20% according to large US study Having late nights at the weekend increases your risk of heart attacks and strokes by over 20%, research suggests A US study put sleep tracking devices on 10,000 Americans for six months and has revealed unprecedented insights into the impact of varying the time you go to bed. Scientists analysed the data on over one million nights’ sleep looking at duration as well as the quality of sleep. Changes in sleep timing from night to night over about a six-month period were linked to a 20%-23% higher risk of heart attack, stroke and heart failure. Every half hour increase in how much a person's sleep length varied from night to night was associated with a 29% higher risk of having a disease of the heart muscle, which leaves the heart unable to pump enough blood through the body, as well as a 20% higher risk of heart failure. To see more of the stories you love from The Mirror just click on the link here to find them at the top of your feed. Lead researcher Dr Nguyen Minh Tuan Viet, of Harvard Medical School in the US, 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." It comes after the Mirror reported on research emerging from Europe’s biggest heart conference which showed that it was still worth having a weekend lie-in - even if it means disrupting your regular wake-up routine. The average British adult gets between 6 and 6.4 hours of sleep per night - below the recommended 7 to 9 hours. The new study being presented at the American Heart Association's Scientific Sessions 2026 in Chicago saw sleep tracked for six months before participants were followed for four years to see if they suffered heart issues. It also looked at how much of participants’ night was spent in light, deep and rapid eye movement (REM) sleep. REM sleep is periods of rapid brain activity when people have dreams and it makes up around a quarter of our night’s sleep. The study measures participants’ number of "sleep cycles" each night which is the interval from the end of one REM period to the end of the next, including the light and deep sleep stages in between. Having a greater number of complete "sleep cycles" each night led to 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. Previous research has shown going to bed late, alcohol near bedtime and certain medications can disrupt the restorative periods of REM sleep. Dr Minh Tuan Viet, who also works as a neuroscientist at Boston Children's Hospital, 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 he Mirror attended the European Society of Cardiology’s annual congress in Munich in August and heard how catch up sleep could reduce the risk of high blood pressure among people having a late night at the weekend. Scientists behind the seven-year study of 41,000 adults being presented at the conference said people should not feel guilty about sleeping in at the weekend as it could be the body’s way of recovering. Their analysis identified the perfect amount of catch-up sleep - with a one hour and 27 minute lie-in resulting in the most benefit. Someone getting this amount of extra sleep would be 9% less likely to have high blood pressure.