WASHINGTON — A new study suggests that the 6 percent to 10 percent of Americans who use prescription sleep medications such as zolpidem (Ambien), temazepam (Restoril), eszopiclone (Lunesta) and zaleplon (Sonata) are more likely to develop cancer, and far more likely to die prematurely, than those who take no sleep aids.

The increased rates kick in at really low levels too, the study says. For those prescribed as few as one to 18 sleeping pills in a year, deaths during the period of the new study were more than 3Z\x times greater than for those who got no such prescriptions, the study says. And for patients who took home the largest number of prescriptions for sleep aids — for more than 132 pills per year — the risk of death was five times greater than among those who appeared to take no sleep aids, according to the study, released by the British medical publication BMJ Open.

Studies such as this one do not establish whether sleep drugs are a cause of the increased cancers and deaths or whether, perhaps, those who are at greater risk of dying or developing cancer are simply more likely to seek a prescription for sleep problems. To establish such relationships, clinical trials, which would compare subjects taking sleep medications against those taking a sham drug, would be necessary, said study co-author Dr. Daniel Kripke.

In addition, the “all-cause mortality” used in the study is a crude measure of a drug’s risk, because the measure aggregates a wide range of seemingly unrelated health crises: automobile accidents, injuries, suicides, infectious diseases such as influenza, and chronic conditions, including asthma, diabetes and cancer.