Study: Shock study reveals too much sleep 'could cause a stroke'

Previous studies have suggested a link between sleep and the risk of stroke.

But the new research published last night (WED) in journal Neurology is the first to investigate in detail the link between sleep duration and stroke risk.

Researchers say it is unclear why the link between sleep and stroke risk exists.

Lack of sleep has been linked with factors such as disrupted metabolism and raised levels of the “stress hormone” cortisol, all of which may lead to higher blood pressure and increased stroke risk.

But the findings suggest that the link was independent of normal risk factors for cardiovascular disease.

The study followed 10,000 people aged 42 to 81 and found those who slept longer than eight hours on average at any point faced a 46% greater risk of stroke.

The study found that those who said they slept more than eight hours a night at both points of the study were twice as likely to suffer a stroke as those sleeping between six and eight hours.

Most of them reported sleeping between six and eight hours a day with just one in 10 reporting sleeping for more than eight hours a day.

People who slept less than six hours a day were at an 18% increased risk than those who slept between six and eight hours.

Once they had collected their data the scientists combined their findings with 11 other global studies.

Their final analysis included more than 500,000 people from seven countries and supported the findings of their own research.

Prof Kay-Tee Khaw, senior author on the study, said: “We need to understand the reasons behind the link between sleep and stroke risk.

“With further research, we may find that excessive sleep proves to be an early indicator of increased stroke risk, particularly among older people.”

The study was supported by the Medical Research Council and Cancer Research UK.

Tonight the Stroke Association said the study on sleeping longer “does not provide sufficient evidence to prove that this is of concern”.