Looking at data from 21 countries in seven regions, the research team found that people sleeping more than the recommended eight-hour limit increased their risk of major cardiovascular events, such as stroke or heart failure, and death by up to 41 %.
One possible reason for this could be that people are suffering from basic conditions that cause them to sleep longer which in turn could increase the risk of cardiovascular disease or mortality, the authors of the study explain.  The team, led by Chuangshi Wang, Ph.D. A student at McMaster and Beijing Union Medical College in China also saw an increasing risk among day-wearers.
"Napping by day was associated with an increased risk of cardiovascular events and deaths at six hours [more than]but not in the sleeper [less than] 6 hours a night," Wang said.
Among those who under-lied, "a nap seemed to compensate for the lack of sleep during the night and mitigate the risks," Wang said.
Previous studies on this topic have been conducted mainly in North America, Europe, and Japan. The new study provides a global picture.
But the results are observational, that is, the cause of this association remains unknown.
"Although the results were very interesting, they do not prove to be cause and effect," said Julie Ward, a senior nurse at the British Heart Foundation who was not involved in the study.
Even with less sleep ̵
Signs of Sleep
The study interviewed 116,632 adults between the ages of 21 and 70 from 21 countries about their sleep habits . Participants were then followed for an average of 7.8 years.
The team found that per 1,000 people who slept for the recommended six to eight hours per night, developed 7.8 cardiovascular diseases or died each year. For those who slept six or fewer hours per night, the increase increased to 9.4.
Francesco Cappuccio, professor of cardiovascular medicine and epidemiology at Warwick University, who was not involved in this study, has conducted several studies on sleep and its effects on our sleep health. He says that a lack of sleep is "definitely associated with an increased risk of death".
"If you sleep less for a long time, you are more likely to develop a chronic disease," said Cappuccio. He added that a short sleep duration increases high blood pressure, obesity and diabetes.
However, for those who did not fall asleep, the results were not statistically significant, and the biggest risk was found in those who overslept instead.
In eight to nine hours of sleep, 8.4 out of every 1,000 people developed cardiovascular disease or died each year. For those who slept between nine and ten hours (10.4 per 1,000) and those who slept for more than 10 hours (14.8 per 1,000), this figure increased even further.
This represents a 5%, 17% and 41% increase in risk, respectively, compared to people who fell short of the recommended number of hours.
However, Wang pointed out that too much sleep could be a marker for other causes of cardiovascular disease and death.
Cappuccio agreed, adding, "It's not that long sleep causes death or poor health," but that this can lead to health problems making you sleep more.
Cappuccio mentioned that people who suffer from an unrecognized illness can suffer from prolonged sleep. For example, if someone has a cancer underneath, they become more tired and weaker and tend to sleep longer.
The main approach of the study is that the optimal duration of estimated sleep for adults is six to eight hours a day (Wang) explains.
It's "very important to point out that there are some very simple things that can help you sleep better at night," Ward said, advising people to avoid caffeine in the afternoon or evening, alcohol, and nicotine Can disturb sleep patterns. Exercise and a balanced diet can help, she added.
"Naps could reflect the underlying disease & # 39;
It was found that a midday nap in the Middle East, China in the southeast (19659004) was common to Asia and South America and was associated with a higher risk of death or cardiovascular problems among those who also recommended Had sleep hours at night or more.
However, this has not been the case for people who have slept under six hours a night.
"In these individuals, a nap seemed to compensate for sleep deprivation at night and reduce the risks," Wang said.
But for those who slept well at night, noon sleep became increasingly risky for major cardiovascular events and deaths, "she said.
Cappuccio has previously conducted daily naps on British adults.
" Napping could The underlying disease (fatigue, fatigue ) eventually reflecting morbidity and mortality, could be a symptom of sleep deprivation, as a compensatory catch-up mechanism or even a symptom of circadian malposition, "he said.
The team also did not collect data on insomnia, such as insomnia, referring to the Sc hlaf and could also affect their health.
Wang explained that it is usually not possible to accurately measure sleep time in large population surveys.
The researchers hope that their findings will encourage physicians to question their patients about sleep modes when discussing general lifestyle factors to identify potential underlying health issues.
Salim Yusuf, Professor of Medicine at McMaster University and The Principal Investigator of the PURE study, from which the participants were selected, said, "For physicians, questions about sleep duration and siesta can be helpful in your patient's medical history be to identify persons with high cardiac and blood risk ship problems or death. "