Older people who don’t get a good night’s sleep are at an increased risk of getting hardened blood vessels in the brain, leading to stroke and cognitive impairment, a new study says.

Fragmented sleep, or sleep interrupted frequently during the night, has often been linked with dementia and cognitive decline in past studies, but Dr. Andrew Lim, who is a neurologist at Sunnybrook Health Science Center in Toronto and the author of the study, said in a statement that there were gaps in science’s understanding of the underlying brain changes that resulted in these problems, according to a Live Science report.

“The forms of brain injury that we observed are important because they may not only contribute to the risk of stroke but also to chronic progressive cognitive and motor impairment,” Lim said.

To arrive at their conclusions, Lim and his colleagues examined the brains of 315 people who had autopsies after they died at an average of 90, with 70 percent being women. The study participants had their daily activity and sleep monitored before they died.

They found that 29 percent of the study participants had a stroke, and 61 percent had damage to their brain’s blood vessels. Those who had interrupted sleep were 27 percent more likely to have hardened arteries than those who slept through the night, the study found.

Also, those who had interrupted sleep were 31 percent more likely to have damage to their brains because of oxygen starvation.