Sleeping too much – or too little – increases the risk of heart attack – ScienceDaily

The research, published on September 2 in the Journal of the American College of Cardiology, also found that for people at high genetic risk of heart attack, sleeping between 6 and 9 hours a night can offset this risk.

"This provides the strongest evidence to date that sleep time is a determining factor for heart health, and that's for everyone," said lead author Celine Vetter, assistant professor of integrative physiology. .

For the study, Vetter and co-authors from Massachusetts General Hospital and the University of Manchester analyzed genetic information, self-reported sleep patterns, and medical records of 461,000 British Biobank participants aged 40 to 69. years who had never had a heart attack. followed them for seven years.

Compared to those who slept 6 to 9 hours a night, those who slept less than six hours were 20% more likely to have a heart attack during the study period. Those who slept more than nine hours were 34% more likely.

When researchers focused only on people with a genetic predisposition to heart disease, they found that sleeping between six and nine hours a night reduced their risk of heart attack by 18%.

"It's a bit of a hopeful message that, no matter how risky your heart is, having a good night's sleep can reduce that risk, just like eating healthy, not smoking, and other lifestyle approaches can do it, "said lead author Iyas Daghlas. , medical student at Harvard.

Previous research has long suggested an association between sleep and heart health, but as these studies were observational – it was about looking at different groups to determine who was developing a disease – it was difficult to determine whether a sleep insufficient caused heart problems or vice versa.

Many factors can affect both heart health and sleep, making it more difficult to determine causes and effects.

For the new study, researchers used the huge data set of the British Biobank and combined observational and genetic research to ask the question differently.

After taking into account 30 other factors – including body composition, physical activity, socio-economic status and mental health – they found that sleep duration in itself influenced the risk of heart attack independently. of these other factors.

The more people who fell outside the 6-9 o'clock range, the greater the risk. For example, people who slept five hours a night had a 52% higher risk of heart attack than those who slept from 7 to 8 years, while those who slept 10 hours each night were twice as likely to sleep. to have one.

With the help of a method called Mendelian randomization, the researchers then examined the participants' genetic profiles to determine whether people genetically predisposed to a short sleep were more likely to have a heart attack. Twenty-seven genetic variants have been associated with short sleep.

They saw similar patterns emerge and found that short sleep, genetically influenced, was a risk factor for heart attack.

"This gives us even more confidence that there is a cause-and-effect relationship here – that it is the duration of sleep, not something else, that influences heart health," Vetter said. .

The study did not explore the mechanism by which a short or long sleep can increase the risk of heart attack, but previous studies have given some explanations. Too little sleep can have an impact on the lining of the arteries or on the endothelium, on the development of inflammatory cells in the bone marrow, but also on poor dietary options and poor diet (which can in turn affect weight and, therefore, heart health). Too much sleep can also stimulate inflammation in the body, which is also associated with cardiovascular disease.

The authors hope that the study will educate physicians, public health agencies and the public about the benefits of sleep for heart and heart health.

"Just like working and eating healthy can reduce your risk of heart disease, sleep can also," said Vetter.