Little sleep, or too much, is not good for cardiovascular health

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The time you sleep, including daytime naps, is related to their risk of developing cardiovascular disease and death, according to a study of more than 116,000 people in seven regions of the world, published today in the "European Heart Journal".

The study concludes that both short sleep, as to do so in great quantity is not good for our cardiovascular health . Researchers have seen that people who slept longer than the recommended -for six to eight hours a day - had a higher risk of dying or developing disease, cardio-or cerebrovascular diseases.

as Well, the report notes that, compared with people who slept the recommended time, those who slept eight to nine hours a day, had an increased risk of 5%; people who slept between nine and ten hours a day had an increased risk of 17%, and those who slept more than ten hours a day had an increased risk of 41%. The study also found a risk increase of 9% for people who slept a total of six hours or less, but this finding was not statistically significant.

lack of sleep may be a factor associated with death and cardiovascular disease, while too much sleep can indicate diseases that increase the risk

The researchers have seen, also, that for every 1,000 people who sleep six hours or less per night, 9,4 developed cardiovascular disease or died at one year; this occurred 7.8 of them that slept six to eight hours, with 8.4 of those that slept eight to nine hours, 10,4 of those who slept nine to ten hours and 14.8 of those who slept more than ten hours.

The lead author, Chuangshi Wang, McMaster University, in Ontario (Canada), explains that the work"shows that the optimal duration of sleep estimated six to eight hours a day for the adults." Now, he says, because it works from an observational study, "can only show an association rather than a causal relationship; that is to say, we can not say that the excess of dream in and of itself to cause cardiovascular disease. However -he adds - the lack of sleep could be a factor associated with death and cardiovascular disease, while too much sleep can indicate diseases that increase the risk."

21 countries

unlike other studies, which have suggested a relationship between sleep and death or cardiovascular disease but with conflicting results, this research has examined 116.632 adults between 35 and 70 years in 21 countries with different income levels in seven geographical regions ( North America and Europe, South America, Middle East, south Asia, southeast Asia, China and Africa ). All of them were part of the study 'Epidemiology Rural Urban Foresight' ( PURE ), which began in 2003.

During the follow-up of almost eight years, 4.381 people died and 4.365 suffered a cardiovascular problem important, like a heart attack or a stroke.

The results also show that people who slept six hours or less per night, but threw a nap in day and, therefore, slept an average of 6.4 hours per day in total, recorded a slightly higher risk compared with those who slept between six and eight hours per night without a nap during the day, but this finding was not statistically significant.

Naps

"Although daytime naps are associated with an increased risk of death or cardiovascular problems in people who get enough sleep or for a longer time throughout the night, it was not so in people who slept less than six hours per night. In these people, a nap during the day seemed to compensate for the lack of sleep at night and to mitigate the risks," adds Wang.

professor Salim Yusuf, principal investigator of the study PURE, and professor of McMaster University concluded: " We should try to sleep between six and eight hours a day . It might be useful for doctors to include questions about the duration of sleep and if you sleep nap during the day in the medical histories of their patients to identify people with high risk".