The sleeping pill Ambien seems to unlock a primitive desire to eat in some patients, according to emerging medical case studies that describe how the drug’s users sometimes sleepwalk into their kitchens, claw through their refrigerators like animals and consume calories ranging into the thousands.
The next morning, the night eaters remember nothing about their foraging. But they wake up to find telltale clues: mouthfuls of peanut butter, Tostitos in their beds, kitchen counters overflowing with flour, missing food, and even lighted ovens and stoves. Some are so embarrassed, they delay telling anyone, even as they gain weight.
“These people are hell-bent to eat,” said Dr. Mark Mahowald, who is director of the Minnesota Regional Sleep Disorders Center in Minneapolis and is researching the problem.
He and colleagues are preparing a scientific paper based on their findings that a sleep-related eating disorder is one of the unusual side effects showing up with the widespread use of Ambien. Researchers at the Mayo Clinic in Rochester, Minn., have made similar findings.
A woman in Salinas, Calif., whose case is to be included in the Minnesota study, said she would awaken to find candy bar wrappers next to her bed and Popsicle sticks on the floor near the refrigerator. She blamed her husband and sons before finally believing their claims that she was eating at night, unaware.
Worried that she would choke, “my son was so afraid at night, he’d come sit by the bed and watch me,” said the woman, Brenda Pobre, 54. Despite seeing several doctors, Ms. Pobre did not link Ambien to her nocturnal eating until after she gained 100 pounds.
Spurred in part by consumer advertising, more than 26 million prescriptions for Ambien were dispensed in this country last year, an increase of 53 percent since 2001.
Sanofi-Aventis, the French company that makes the drug, has defended its safety in 13 years of use in the United States. A company spokeswoman, Melissa Feltmann, said, “Sanofi-Aventis has received reports of people eating while sleepwalking and those reports, like all reports of adverse events, have been provided to the U.S. Food and Drug Administration.”
Ms. Feltmann said that the package insert for Ambien warns that a sleep-related eating disorder may occur, but she cautioned that every case reported in patients taking Ambien might not necessarily be caused by the drug.
Most of the people who use Ambien say the drug puts them to sleep, and they wake up without incident. But several doctors and a number of patients say that sleep-eating is one of a variety of unusual reactions to the drug.
The reactions range from fairly benign sleepwalking episodes to hallucinations, violent outbursts and, most troubling of all, driving while asleep, a subject explored in an article last week in The New York Times. The Food and Drug Administration has said in response to a Times reporter’s query that it would monitor the drug’s safety record.
Dr. Carlos H. Schenck, a sleep disorders expert in Minneapolis and the lead researcher on the study, estimates that thousands of Ambien users in the United States experience sleep-related eating disorders while taking the drug.
Ambien, the brand name used in the United States for the drug zolpidem, is sold in some countries under the brand names Stilnox and Stilnocht. In this country it is by far the biggest seller among a group of similar prescription sleeping drugs that include Lunesta and Sonata.
The drug’s growth into a product worth $2.2 billion in annual sales in the United States has been fueled partly by consumer advertising. Sanofi-Aventis spent $130 million to advertise the product in 2005, more than double the $61 million it spent in 2004, according to figures released by TNS Media Intelligence.
No cause has been found for sleep-related eating disorder, but Dr. Schenck says he believed that it happened when the brain confuses two basic instincts: sleeping and eating. “Those two become linked,” he said. “In the sleep stage you eat. I think two instinctual behaviors become intertwined.”
Along with Dr. Mahowald and other colleagues at the University of Minnesota Medical School and the Hennepin County Medical Center in Minneapolis, Dr. Schenck has identified 32 Ambien users having sleep-related eating disorder with amnesia, part of a group of case studies they are planning to publish.
Often patients with sleep-related eating disorder caused by Ambien realize they have an eating problem, but do not associate it with the sleeping pill until they find a doctor who is aware of the relationship, Dr. Schenck said.
Zolpidem is a prescription short-acting nonbenzodiazepine hypnotic that potentiates gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter, by binding to benzodiazepine receptors which are located on the gamma-aminobutyric acid receptors. Zolpidem is used for the short-term treatment of insomnia. It works quickly (usually within 15 minutes) and has a short half-life (2-3 hours). Some trade names of zolpidem are Ambien, Stilnox, Stilnoct, Hypnogen, Zolt, Zolfresh, Nimadorm, Sanval, and Myslee. Its hypnotic effects are similar to those of the benzodiazepine class of drugs, but it is molecularly distinct from the classical benzodiazepine molecule and is actually classified as an imidazopyridine. Flumazenil, a benzodiazepine receptor antagonist, which is used for benzodiazepine overdose, can also reverse zolpidem’s sedative/hypnotic effects. As an anticonvulsant and muscle relaxant, the beneficial effects start to emerge at 10 and 20 times the dose required for sedation, respectively. For that reason, it has never been approved for either muscle relaxation or seizure prevention. Such drastically increased doses are more inclined to induce one or more negative side effects, including hallucinations and/or amnesia.