Monday, September 24, 2007

Too much sleep as harmful as not enough

Researchers, from the University of Warwick and University College London, have found that lack of sleep can more than double the risk of death from cardiovascular disease. However, they have also found that too much sleep can more than double the risk of death.

The study examined the sleep patterns of participants aged 35-55 at two points in their lives -- 1985-88 and 1992-93 -- and then tracked their mortality rates until 2004.

The optimal amount of sleep for the average adult is seven hours.

Individuals who cut the duration of their sleep from seven hours to five hours a night had a 1.7-fold increased risk of death from all causes. They also had twice the increased risk of death from a cardiovascular problem. "Short sleep has been shown to be a risk factor for weight gain, hypertension and Type 2 diabetes sometimes leading to mortality,' said Francesco Cappuccio, an author of the study.

Individuals who increased the number of hours they slept per night from seven to eight hours or more were more than twice as likely to die as those who kept sleeping for seven. They were also more likely to die from non-cardiovascular diseases.

Personally, I don't believe these kind of reports completely. I'll probably believe 30-40%. Just like coffee or other food reports... One report will say that it is good for you... Another report will say that it is bad for you. Even though the researchers take into account other possible factors (such age, sex, marital status, employment grade, smoking status, physical activity, alcohol consumption, etc), there are many things that they couldn't account for. People are not robots. They don't do the same thing over and over again. People's habits change from time to time. I don't think researchers can take all factors into account. Furthermore, 10,308 people out of 6.7 billion people in the world participated in this research. The sample size is extremely small. Hopefully, more sleep related researches will be done in future.

CBC News
Science Daily

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