Healthy living

Seven hours sleep a night best

Seven hours a night best for health Too few linked to heart disease

People who regularly sleep more or fewer than seven hours a night could be increasing their risk of heart disease, new research has found.

A study of more than 30,000 adults found that cardiovascular disease - angina, heart attack and strokes - was twice as likely to occur in people who slept for less than seven hours a night compared with those who slept for seven hours.

In the study, participants were asked to fill in questionnaires about their health and lifestyle, including questions about their sleep patterns.

People who slept for fewer than five hours a night had double the risk of developing heart disease compared to those who got a good seven hours.

The findings showed the risk was highest in women, and in those over the age of 60.

Sleeping for more than seven hours was also shown to be associated with an increased, but less dramatic risk, as people who slept for more than nine hours a day were one and a half times more likely to develop heart disease.

Although the researchers could not explain why too much or too little sleep could affect the health of your heart, they suggested that short sleep duration may be related to changes in the body's metabolism and hormonal functions.

Sleep deprivation is associated with impaired glucose tolerance, reduced insulin sensitivity and elevated blood pressure, all of which increase the risk of hardening of the arteries, they said.

Long sleep duration may be related to an underlying sleep-related breathing disorder or poor sleep quality, researchers said.

"Sleep disturbances may be a risk factor for cardiovascular disease even among apparently healthy subjects," said study leader Dr Anoop Shankar from the Department of Community Medicine at West Virginia University.

"Our study findings may have important clinical and public health implications, such as screening for changes in sleep duration by primary care physicians as a potential risk factor for cardiovascular disease, or initiating public health initiatives focussing on improving sleep quality and quantity," Dr Shankar added.

The findings are published in the journal Sleep.

This article was published on Thu 23 December 2010

Image © DuĊĦan Zidar -

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