Health risk of sleeping for less than six hours: Study says too little rest can raise the risk of stroke or heart disease

  • Research published in Journal of the American Heart Association shows too little sleep is associated with higher risk of death
  • The risk hits those with metabolic syndrome - diabetes, high blood pressure and obesity
  • It's particularly strong in those with elevate blood pressure or poor metabolism 

Having too little sleep could put people at risk from heart disease, warns new research.

The study found that having less than six hours sleep a night was associated with a higher risk of death in people with metabolic syndrome – a combination of diabetes, high blood pressure and obesity

Researchers said the effect was particularly strong in those with elevated blood pressure or poor glucose metabolism.

Having too little sleep could put people at risk from heart disease, warns new research. File image

Having too little sleep could put people at risk from heart disease, warns new research. File image

People with a common cluster of risk factors for heart disease and diabetes were around twice as likely to die of heart disease or stroke as people without the same set of risk factors if they failed to get more than six hours of sleep, according to the study published in the Journal of the American Heart Association.

For those who got more sleep, the risk of death was more modest.

The study is the first to measure sleep duration in a laboratory rather than relying on patient reports, and the first to examine the impact of sleep duration on the risk of death in those with a common cluster of heart disease risk factors.

The researchers randomly selected 1,344 adults with an average age of 49 who agreed to spend one night in a sleep laboratory.

Based on their test results, 39.2 per cent of the participants were found to have at least three of the risk factors, that when clustered together are known as the metabolic syndrome.

For the study, the cluster included body mass index (BMI) higher than 30 - the standard definition of being obese, as well as elevated total cholesterol, blood pressure, fasting blood sugar and triglyceride levels.

During an average follow-up of 16.6 years, 22 per cent of the participants died.

Compared to people without the same cluster of risk factors, those with metabolic syndrome who clocked more than six hours of sleep time in the lab were about 1.49 times more likely to die of stroke during the follow-up period.

But those who slept less than six hours in the lab were about 2.1 times more likely to die of heart disease or stroke.

The risk affects those with metabolic syndrome, a combination of diabetes, high blood pressure and obesity. File image

The risk affects those with metabolic syndrome, a combination of diabetes, high blood pressure and obesity. File image

The short sleepers with metabolic syndrome were also 1.99 times more likely to die from any cause compared to those without metabolic syndrome.

The relationship was particularly striking because the researchers adjusted for sleep apnoea - sleep interrupted by pauses in breathing that is a known heart disease risk.

Study lead author Doctor Julio Fernandez-Mendoza, of Penn State College of Medicine in the US, said: 'If you have several heart disease risk factors, taking care of your sleep and consulting with a clinician if you have insufficient sleep is important if you want to lower your risk of death from heart disease or stroke.'

He noted that sleep lab studies are often used to rule out sleep apnoea, but doctors should also note insufficient sleep in the lab because it may signal a higher risk of death in patients with risk factors for heart disease.

Dr Fernandez-Mendoza said the research was an observational study, so the results cannot establish a cause-and-effect, only an association between short sleep and mortality in people with the metabolic syndrome.

He added: 'Future clinical trials are needed to determine whether lengthening sleep, in combination with lowering blood pressure and glucose, improves the prognosis of people with the metabolic syndrome.' 

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