Insomnia may be linked to an increased risk of heart attack and stroke, according to recent research published in the European Journal of Preventive Cardiology.

The symptoms of insomnia—difficulty initiating sleep, difficulty maintaining sleep, or non-restorative sleep—were associated with 27%, 11%, and 18% higher risks of cardiovascular and stroke events, according to Qiao He, study author and Master’s degree student at China Medical University.

Although so many people experience insomnia, past reasearch has been inconsistent regarding whether it can be linked to heart attack or stroke risk, which is what led reseachers to conduct the analysis, according to He.

Researchers analyzed 15 studies—a total of 160,668 people—to find out whether there is an association between insomnia and death from cardiovascular disease, stroke, or a combination of health events.

“The underlying mechanisms for these links are not completely understood,” He said in a press release. “Previous studies have shown that insomnia may change metabolism and endocrine function, increase sympathetic activation, raise blood pressure, and elevate levels of pro-inflammatory and inflammatory cytokines—all of which are risk factors for cardiovascular disease and stroke.”