Health risks rise if you don’t get six to eight hours’ sleep a night
Failing to hit the sweet spot of six to eight hours’ sleep a night is linked to increased risk of heart disease and death, according to a study of 116,000 people worldwide.
Too much sleep appeared to be more dangerous than too little. The longer people slept beyond eight hours, including naps, the greater their risk of dying during the study or developing diseases of the heart or blood vessels in the brain.
Those who slept between eight and nine hours a day had a 5 per cent increased risk compared with those who totalled six to eight hours. The increased risk for those sleeping between nine and 10 hours was 17 per cent, and for those sleeping more than 10 hours a day 41 per cent.
Chuangshi Wang, a PhD student at the Chinese Academy of Medical Sciences and the study’s lead author, said: ‘‘Our study shows that the optimal duration of estimated sleep is six to eight hours per day for adults. Given that this is an observational study that can only show an association rather than proving a causal relationship, we cannot say that too much sleep per se causes cardiovascular diseases.
‘‘However, too little sleep could be an underlying contributor to death and cases of cardiovascular disease, and too much sleep may indicate underlying conditions that increase risk.’’
She said that daytime naps appeared to mitigate the risks of less sleep at night for people who slept under six hours, but was associated with higher health risks in those with sufficient or longer sleep at night.
The study, published in the
European Heart Journal, found that before statistical adjustments 9.4 people in every 1000 sleeping six or fewer hours each night developed cardiovascular disease or died each year. The same was true for 7.8 people of every 1000 sleeping six to eight hours, 8.4 of those sleeping eight to nine hours, 10.4 of those sleeping nine to 10 hours and 14.8 of those sleeping more than 10 hours.
The study involved 116,632 adults aged between 35 and 70 in 21 countries with different income levels in North America and Europe, South America, the Middle East, South Asia, Southeast Asia, China and Africa. Over eight years, 4381 people died and 4365 suffered a heart attack or stroke.
‘‘The general public should ensure that they get about six to eight hours of sleep a day. On the other hand, if you sleep too much regularly, say more than nine hours a day, then you may want to visit a doctor to check your overall health,’’ Salim Yusuf, the principal investigator of the study, said. ‘‘For doctors, including questions about the duration of sleep and daytime naps in the clinical histories of your patients may be helpful in identifying people at high risk of heart and blood vessel problems or death.’’ –