(NEWSER) – Sleeping more than eight hours a night? That may be too much of a good thing, because you’re more likely to suffer a stroke, according to a study out of the University of Cambridge. Researchers analyzed the sleep patterns of nearly 10,000 people ages 42 to 81 in the UK, and they report in the journal Neurology that based on nearly a decade of follow-up and 346 reported strokes, older adults who sleep more than eight hours a night are 46% more likely to suffer a stroke than adults who slept six to eight hours. That risk is actually four times greater when people went from sleeping for less than six hours at the beginning of the study to more than 8 as the years passed, per a Eureka Alert press release.
The researchers adjusted for several factors, including age and sex, and their findings were strikingly consistent with what they found in a review of the combined data of 11 similar studies spanning 560,000 people in seven countries. But in terms of age and sex, the Los Angeles Times notes the following: The link between the risk and sleep length was a little stronger for women, and the increased stroke risk was only seen in those eight-plus-hours sleepers who were 63 or older. The researchers caution that it remains unclear whether longer sleep duration is a symptom or cause of stroke risk. Says one, “With further research, we may find that excessive sleep proves to be an early indicator of increased stroke risk.” (Experts have just revealed how much sleep you should be averaging a night based on your age.)