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Oversleeping linked to increased mortality

Oversleeping linked to increased mortality - Featured Image

It’s not just smoking and high alcohol consumption that we should advise our patients to avoid if they want to live a long life.

A Sydney University study has found that regularly sleeping longer than nine hours a night also can increase the risk of mortality.

The study, published in PLOS One, found that on its own, regular oversleeping meant a 44% increase in risk of death over the six-year study period.

It also found that sitting in a chair for more than seven hours in a 24 hour period can be a big no-no for health.

The researchers gave a lifestyle questionnaire to 231,048 Australians aged 45 years or older who were participating in the Sax Institute’s 45 and up study. The participants were asked to score six health behaviours.

The 6 deadly behaviours are

  • Alcohol consumption
  • Poor diet
  • Inactivity
  • Smoking
  • Spending more than seven hours a day sitting down
  • Sleeping for more than nine hours

Over 90% of the participants had one of the 30 most commonly occurring risk factors and combinations including physical inactivity, sedentary behaviour, and/or long sleep duration. Combinations involving smoking and high alcohol consumption were more highly associated with all-cause mortality.

Dr Melody Ding, one of the study authors, told ABC Radio: “The most intriguing was the 44% risk increase of those who are sleeping more than 9 hours a week. When you combine too much sleep with physical inactivity… then you find the risk for death has increased 149%.

“People who are sleeping too much, sitting a lot and also not being physically active then you’re looking at a combined risk increase of four times.”

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Another author, Associate Professor Emmanuel Stamatakis told Fairfax Media: “One of the possible explanations is ‘reverse causality’. Long sleeping times could be indicative of an underlying, undiagnosed disease.”

However he also said the way the survey was written could be a possible explanation:  “In the survey, people were asked ‘How long did you sleep?’ This most likely elicits an answer to the question: ‘How long were you in bed?’

“This says nothing about the quality of the sleep,” Dr Stamatakis said. “So, reported long sleep duration could in fact be indicative of fragmented, restless and poor-quality sleep.”

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The results founds a person who has all six bad habits is more than five times as likely to die during a six-year period as one who is very clean-living.

Interestingly, high alcohol on its own was the least risky behaviour, with just an 8% increased mortality.

Dr Stamatakis said this shouldn’t give people “licence to drink”.

“General population studies show exactly the opposite result. These show that harmful effects from alcohol start from moderate consumption levels,” he said.

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