Popular prescription sleeping pills like Ambien and Lunesta may increase the risk of developing cancer and premature death, according to a study published in the medical journal BMJ Open.

Researchers at the Scripps Clinic in La Jolla, CA and the Jackson Hole Center for Preventive Medicine in Jackson, WY tracked more than 10,000 people given prescriptions for sleeping pills for at least three months and for as long as four years.

They found that those who took just one to 18 sleeping pills a year died at a rate three times higher than those who didn’t take the medications at all. For patients who took more than 132 pills per year, the rate of death was five times greater.

In addition, the study found a modest but statistically significant increase in the incidence of cancer among those taking sleep medications — the heaviest users of prescription sleep aids were 35 percent more likely to be diagnosed with cancer during the study period compared to those who’d never used the drugs.

Still, doctors were quick to point out none of this establishes a cause and effect. For example, it’s possible that those who are at greater risk of dying or developing cancer are simply more likely to have sleep problems and seek a prescription for them.

More From WFNT