Regularly sleeping more than eight hours every night doubles your risk for stroke, say researchers from the University of Cambridge. It also depends on how long you've been over-sleeping; those at twice the risk had been sleeping the longer hours for at least 10 years, but the risk reduces to around 46 per cent if you've done so for far less a time.
There's also a slight risk for those who regularly sleep six hours or less, but it's not significant and could be explained by other causes, the researchers say.
They made the connection after they analysed the health and sleeping habits of 10,000 participants aged between 42 and 81, who were monitored for nearly 10 years. Over that time, 346 of the participants suffered a stroke, and the researchers discovered the risk was greater in those who were over-sleeping. Those who were over-sleeping at the beginning and end of the 10 years of the study had double the risk.
While the connection seems to be real enough, the researchers are puzzled as to the reason.
(Source: Neurology, 2015; doi: 10.1212/WNL.0000000000001371)