The most widely prescribed sleeping pills can cause strange behavior, including driving and eating while asleep, the Food and Drug Administration said Wednesday, announcing that strong new warnings will be placed on the labels of 13 drugs. The FDA also ordered the producers of Ambien, Lunesta and 11 other commonly used sleeping pills to create patient fliers explaining how to safely use them. The fliers, which the FDA says it requires when it sees a significant public health concern, will be handed out at pharmacies when consumers fill their prescriptions. Although the FDA says that problems with the drugs are rare, reports of the unusual side effects have grown as use of sleeping pills has increased. U.S. sales of Ambien and Lunesta alone last year exceeded $3 billion, fueled by advertising. Last year makers of sleeping pills spent more than $600 million on consumer ads. The FDA also received reports of people making phone calls, purchasing items over the Internet or having sex under the influence of sleep medication. The consumers said they had no recollection of the events that occurred after they took their pills and headed for bed. An FDA official said Wednesday that the activities associated with the drugs went beyond mere sleepwalking. “We do believe that sleepwalking is different from these behaviors,” said Dr. Russell Katz, the FDA’s director of neurology products. “Sleepwalking is considered more of a reflex. These behaviors are complex, and they’re different fundamentally because of the complexity. People get up, they take their car keys, and they go drive. As you might imagine, that might be potentially dangerous to the patient and others as well.” Katz said drinking alcohol may increase the chances of a reaction. An Atlanta defense lawyer, William C. Head, said he had received calls from people around the world who had been charged after using such medications. “Ninety percent of these cases involve alcohol as well,” Head said.160Want local news?Sign up for the Localist and stay informed Something went wrong. Please try again.subscribeCongratulations! You’re all set! The FDA review was prompted, in part, by queries from The New York Times after some users of the most widely prescribed drug, Ambien, started complaining about unusual reactions, ranging from fairly benign sleepwalking episodes to hallucinations, violent outbursts, nocturnal binge eating and – most troubling of all – driving while asleep. Night eaters said they woke up and found Tostitos and Snickers wrappers in their beds, food missing from the kitchen, counters covered with flour from baking sprees and even stoves turned on. Sleep-drivers reported going to bed and awakening at roadside in their underwear or nightclothes. The reports gained credence from scientific studies. Dr. Carlos H. Schenck and Dr. Mark W. Mahowald of the University of Minnesota said that they had been studying cases of nearly 30 Ambien users who developed unusual nighttime eating disorders. In some cases, the patients had gained more than 100 pounds. A forensic toxicologist in Wisconsin, Laura J. Liddicoat, gave a presentation at a national meeting on six instances of Ambien-impaired driving. In May 2006 in Washington, Rep. Patrick Kennedy, D-R.I., blamed Ambien when he crashed his car near the Capitol.