Sleeping more than eight hours a day has been linked to an increased risk of stroke by researchers who studied the sleeping habits of almost 10,000 people.

The decade-long study of 9,692 people, aged 42 to 81, logged how much sleep participants had each day over a four-year period.

The news wasn’t good for those who like a lie-in, with 346 of the study subjects suffering strokes.

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After allowing for a range of variables, the researchers found that people who slept more than eight hours a day were 46 per cent more likely to have had a stroke than those who slept six to eight hours.

The British study, published online this month in the journal Neurology and reported in The New York Times, also found the risk of stroke was higher among people who reported their need for sleep had increased over the study period.

The authors warned the data on sleep duration depended on self-reports, which can be unreliable.

“We don’t have enough evidence to apply this in clinical settings” said the lead author, Yue Leng, a doctoral candidate at the University of Cambridge.

“We don’t want people to think if they sleep longer it will necessarily lead to stroke.”

But while it might not cause stroke, the authors said sleeping more may be an early symptom of disease that leads to it.

“It could be that there’s already something happening in the brain that precedes the stroke risk and of which excessive sleep is an early sign,” Ms Yue Leng said.