We are constantly instructed to get enough sleep, but scientists warn that even getting too much can be harmful.
Researchers from the University of Galway, Ireland, analyzed data from 5,000 people, half of whom had already had a stroke.
Participants who slept more than nine hours a night were twice as likely to have a stroke than those who got the standard seven hours.
The results also showed that people who slept less than five hours a night were three times more likely to have a stroke. The study was observational, meaning it couldn’t prove whether too much or too little sleep made stroke more likely.
Researchers have warned that sleeping more than nine hours a night is bad for your health (stock image)
This graph shows the risk of stroke (squared) by the number of hours of sleep per night. The risk increases when someone sleeps less or more than the recommended seven to nine hours per night
The Centers for Disease Control and Prevention (CDC) says everyone should get at least seven hours of sleep each night.
But data suggests that a third of Americans don’t even get that much — while about one in 20 sleeps more than nine hours.
Sleeping too long has already been linked to multiple health problems, including heart disease, diabetes and obesity.
Dr. Christine McCarthy, a sleep scientist who led the study, said: ‘Our results suggest that sleep problems should be an area of focus for stroke prevention.
“With these results, doctors would be able to have conversations with people who have sleep problems sooner.”
It wasn’t clear why too much sleep increased stroke risk, but the scientists suggested it could be an indicator of other health problems.
This includes a sedentary lifestyle, anemia or depression – all of which are known to increase the risk of stroke – or a higher likelihood of obesity.
On the other hand, too little sleep is also known to increase stroke risk due to higher blood pressure levels, inflammation, and an increased risk of obesity and type 2 diabetes.
In the latest study, published in the journal Neurologyscientists analyzed data from 5,000 people who participated in the INTERSTROKE study, which followed patients and matched controls from 32 countries.
The participants averaged about 62 years old, while two out of three were men.
They were all asked to complete a survey about their sleep, including how many hours they got, the quality of it, whether they took naps and whether they snored, sniffed or had breathing problems during sleep.
The results showed that in the stroke group, 151 people slept longer than nine hours. In comparison, in the group without a stroke, 84 slept that long.
Data also showed that in the stroke group, 162 people slept less than five hours, while this fell to 43 in the non-stroke group.
The scientists also found that people who sniffed while they slept — a sign of sleep apnea — were three times more likely to have a stroke than those who didn’t.
People who snored were 91 percent more likely to have a stroke, data also suggested.
Dr. McCarthy added: ‘Not only do our results suggest that individual sleep problems can increase a person’s risk of stroke, but having more than five of these symptoms can lead to five times the risk of stroke compared to people who do not have sleep problems. . ‘
Limitations of the study included that all sleep data was self-reported.
Participants did not need to wear a wrist device at night for any period of time to record their actual sleep patterns.
They also weren’t asked to record when they snored or snored while they slept, or to show a doctor’s note proving sleep apnea.
Funding for the study was led by the Canadian Institutes of Health Research, the country’s leading health research organization.