Are your sleeping pills killing you?

People who use sleeping pills regularly are far more likely to die prematurely than those who don’t, according to a new study. Researchers compared the health records of more than 10,000 sleeping-pill users with those of other patients of similar ages and health histories who didn’t use the drugs. They found that the heaviest sleeping-pill users were five times more likely to die of any cause over the study period—and 35 percent more likely to develop cancer— than were people who nodded off without the drugs. Even those who took only between 1 and 18 sleeping pills per year had 3.6 times the death risk of nonusers, WebMD.com reports.

Sleeping pills “could be as risky as smoking cigarettes,” says study author Daniel Kripke, a psychiatry professor at the University of California, San Diego. He estimates that the drugs, including popular brands J like Ambien, Restoril, and Lunesta, could be responsible for as many as naif a million fatalities per year in the U.S. Other experts caution that the association of higher death rates with sleeping-pill use doesn’t prove that the drugs cause fatal illness; it might be that people who have serious sleep problems also have other health conditions that lead to early death.