You snooze, you lose.

A new study published in the journal Neurology suggests that getting too much sleep can be damaging.

The Centers for Disease Control and Prevention recommends at least seven hours of sleep per night — but researchers found that people who sleep more than nine hours per night had an increased chance of suffering a stroke.

“Our results suggest that sleep problems should be an area of focus for stroke prevention,” Dr. Christine McCarthy, a sleep scientist who led the study, said. “With these results, doctors could have earlier conversations with people who are having sleep problems.”

Scientists from the University of Galway in Ireland analyzed data from 4,496 people — about half of which had already suffered a stroke — who participated in the INTERSTROKE study, an international case-control study of patients with first acute stroke matched with controls of age and sex across 32 countries.

Participants were on average 62 years old and two in three were male. They were asked to complete a questionnaire on their sleeping habits including how many hours of sleep they get, sleep quality, whether or not they take naps, and if they snore, snort or have breathing problems while sleeping.

All data on sleep was self-reported by the participants, and they were not required to wear a device at night for any period to actually record sleep patterns or provide recordings of snores and snorts. If the participants had sleep apnea, they did not have to provide a doctor’s note to prove it.

In the group of those who had suffered strokes, 151 people slept longer than nine hours, while in the non-stroke group, only 84 people slept that long.

Findings also showed that 162 people in the stroke group slept less than five hours while only 43 people in the non-stroke group slept that little.

People who snored while sleeping were three times more likely to have a stroke than those who didn’t, and people who snored were 91% more likely to have a stroke.

Regularly oversleeping has previously been linked to other health problems including obesity, diabetes, heart disease and increased risk of death, according to Healthline.

It’s not immediately clear why too much sleep leads to an increased chance of stroke, but the researchers suggested it could be due to other health issues such as anemia, depression or a sedentary lifestyle.

On the other hand, getting too little sleep is linked to health problems such as heart and kidney disease, high blood pressure, diabetes, as well as stroke. According to the CDC, 1 in 3 adults in the US don’t get enough sleep.

The study was observational, which means it couldn’t directly prove whether too much or too little sleep was more likely to increase the chance of suffering a stroke, however, scientists found that any sleep disturbance symptoms were associated with a greater risk of stroke.

“Not only do our results suggest that individual sleep problems may increase a person’s risk of stroke but having more than five of these symptoms may lead to five times the risk of stroke compared to those who do not have any sleep problems,” McCarthy said.

Researchers noted that future trials are needed in order to determine if sleep intervention is efficient in terms of stroke prevention.