Strokes often occur during sleep. So what do you do when you wake up?

Strokes that occur during sleep are not rare. According to a study released Monday, about one in seven strokes take place during sleep. That high number raises questions about how to best help people who have strokes during sleep.

An emergency treatment can greatly reduce the damage caused by strokes. But the medicine, called tissue plasminogen activator (tPA), must be given at a hospital within a few hours after the first symptoms begin. During the day, it’s possible to detect the first signs of a stroke. But people who awaken having had a stroke during sleep are at a big disadvantage.

According to the new study, studies are needed to learn ways to identify which people are mostly likely to benefit from tPA treatment even if their symptoms started during sleep. The study, of 1,854 people who had ischemic strokes, found that 14% had symptoms upon awakening. There were few differences between wake-up strokes and non-wake-up strokes, the authors said. People with wake-up strokes tended to be slightly older and had more severe strokes. But the researchers estimated that many of those people with wake-up strokes could have been treated with tPA.

“This is a group of patients that should be a focus for future studies,” said the lead author of the study, Dr. Jason Mackey, of the University of Cincinnati, in a news release. “It’s likely that some of these strokes occurred immediately prior to awakening, and people would benefit from treatment.”

The study was published in the journal Neurology.

Related: Blacks suffering a stroke are more likely to call a friend than 911, study finds

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