Sleep apnea, a potentially serious disorder in which breathing is repeatedly interrupted during sleep, is associated with certain health risks, including an increased risk of cardiovascular disease. These findings have prompted some people to wonder if these health risks extend to those suffering from insomnia, or difficulty falling and staying asleep, since it had previously been linked to sleep apnea. Now, a new study has found there is a link between insomnia and heart disease, but only in those who take sleeping pills.

Dr. Nicholas Vozoris analyzed three years worth of data from the National Health and Nutrition Examination Surveys, which included more than 19,000 people age 20 and over. He observed that people with symptoms of insomnia did not have higher levels of cholesterol (a risk factor for cardiovascular disease) than people without the sleep disorder. However, people with insomnia who took sleeping pills had a 118 percent increased risk of having high levels of low-density lipoprotein (LDL), the so-called “bad” cholesterol.

"What surprised me the most was the finding of higher chances of having elevated bad cholesterol among individuals with insomnia who use sleeping pills [and considering all sleeping pill types, not limited to any specific class]," Vozoris, a respirologist at St. Michael's Hospital in Canada told Medical Daily. "This really hasn't been shown before, that sleeping pills in general may be linked to elevated cholesterol."

This isn’t the first time sleeping pills have been linked to adverse health effects. A 2012 study from Researchers at Scripps Health linked the psychoactive drug to a more than fivefold increase in mortality risk compared to those who don’t use the pills. Higher doses were shown to increase cancer risk by 35 percent. Furthermore, this study revealed that the seemingly innocuous pills contributed to as many as 500,000 deaths in the U.S.

Vozoris considered the possibility that the findings may suggest insomniacs who take sleeping pills simply have more severe insomnia and that more severe insomnia, rather than sleeping pill use, may be the reason for the high LDL cholesterol. However, his findings did not support that.

"Even more severe forms of insomnia, like frequent insomnia, insomnia coupled with daytime fatigue, and insomnia coupled with short sleep time, were not linked with elevated cholesterol," he said. "These latter findings support that the more severe insomnia likely does not explain why individuals with insomnia who take sleeping pills had elevated cholesterol — it may instead be the sleeping pill use."

More than 25 percent of the U.S. population doesn't get enough sleep, while close to 10 percent experiences chronic insomnia, according to the Centers for Disease Control and Prevention. Insufficient sleep has been linked to a number of chronic diseases, including diabetes and depression. The poor sleep condition has also been shown to increase obesity risk, which is a risk factor for heart disease.

Vozoris said more research is needed to confirm a possible link between sleep pill use and high cholesterol levels and to determine if cardiovascular disease “exists with specific types of sleeping pills or with all sedative medications more broadly.”

Vozoris N. Insomnia Symptoms Are Not Associated with Dyslipidemia: A Population-Based Study. Sleep. 2016.