SLEEPING more than eight hours a night could dramatically increase the risk of suffering a stroke, scientists warned yesterday.
Researchers from the University of Cambridge found that having a lie-in on a regular basis may be fatal.
The academics discovered those who regularly slept more than eight hours a night were twice as likely to suffer a stroke compared with average sleepers.
And people who went from sleeping less than six hours a night to more than eight hours were four times as likely to suffer the life-threatening condition where the blood supply is cut off to part of the brain.
The scientists behind the new research say the results of their major study of 10,000 people could save the health service millions of pounds.
Doctors have regularly extolled the virtues of a good night’s sleep to recharge the batteries.
And previous studies found too little sleep may contribute to coronary heart disease and stroke by increasing blood pressure.
But the new findings revealed that people who slept more than eight hours were at a staggering 46 per cent greater risk of stroke than those who slept an average six to eight hours.
In comparison, people who slept less than six hours a day were at an 18 per cent increased risk.
The study found that the risk of strokes doubled in elderly women.
The scientists said the reasons for the link were unclear and more research needs to be carried out to establish why too much sleep could be a killer.
Yue Leng, from the university, said sleeping more was unlikely in itself to directly increase the likelihood of a person having a stroke in their lifetime.
But she said an increased amount of sleep could be a key sign that someone was more likely to suffer from one.
She said: “It’s apparent both from our own participants and the wealth of international data that there’s a link between sleeping longer than average and a greater risk of stroke.
“What is far less clear, however, is the direction of this link, whether longer sleep is a symptom, an early marker or a cause of cardiovascular problems.
“More research is definitely needed.
“This is the first one in the UK to find this association and we found sleeping duration is an indicator.
“It can have a positive impact on public health as research like this could end up saving the NHS money in the long term.”
The research is the first to provide detailed information about the British public and to examine the relationship between a change in sleep duration and stroke risk.