Strange behavior by insomniacs taking prescription drugs, ranging from binge eating to having sex while asleep, have raised safety questions about anti-insomnia medications like Sanofi-Aventis' Ambien.
Researchers in Minnesota are studying cases where insomniacs taking Ambien got up in the middle of the night, binged uncontrollably, then remembered nothing of their actions. The researchers expect to publish data shortly.
Such sleep-induced side effects while on the medications have been around for years, but the incidence is rising because of an explosion in the drugs' use, specialists said.
About 30 million people in the United States take sleep medications, according to the American Academy of Sleep Medicine. By some counts that is a 50 percent jump since the beginning of the decade.
Some of the most serious side effects are short-term memory loss, and accidents involving patients who drive the next day while still feeling drugged.
"Patients who may have engaged in this unusual behavior at night -- it's relatively rare and bizarre," said Donna Arand, president of the American Insomnia Association.
"The daytime sleepiness -- that drugged feeling that people may have -- is probably the most worrisome because of the (vehicular) accidents that can occur."
Other insomnia medications are Lunesta from Sepracor Inc. and Sonata made by King Pharmaceuticals Inc.. In the $2 billion U.S. market for the drugs, market leader Ambien boasts 12 billion nights of patient use.
Increased use of the drugs is spurred in part by heavy advertising and patients may be using the drugs for longer periods than they are intended, experts said.
Consumer group Public Citizen warned that Ambien should only be used on a limited basis because it causes temporary amnesia, according to pharmacist Larry Sasich.
Because the Food and Drug Administration's reporting system is voluntary and anecdotal, "we don't know how big a problem it is ... we have no way to accurately to assess the prevalence," said Sasich a consultant for Public Citizen.
Sanofi-Aventis said sleepwalking is a rare side effect listed on Ambien's label and that it reports all events to the FDA. Still, it had no statistics about the prevalence of sleepwalking.
Ken Sassower, a staff neurologist at Massachusetts General Hospital in Boston said a colleague who had taken one of the sleep drugs could not recall advising residents on rounds the next morning.
"The memory issue may be an infrequent side effect, but when it occurs it can be pretty significant ... certainly that needs to be looked at in a more rigorous way," he said.
Doctors recommended against abruptly stopping the drugs, which can cause withdrawal symptoms including seizures.
"The risk was always there; we are seeing it more now because so many more people are using the drugs," said Merrill Mitler, program director at the sleep disorder unit at the National Institutes of Health.