"About one third of American adults say they have problems falling asleep. And prescriptions for sleeping medications are on the rise, with about 4 percent of people using the drugs, according to the Centers for Disease Control and Prevention."

"But sleep experts say people should exercise caution before deciding to take medication to help them sleep."

"Take the case of Nancy Sherman, a woman in her 60s who lives in Seattle. Sleepless nights started about four years ago when she lived directly above an "end of the line" bus stop. "The buses would leave their motors on all night long and I developed insomnia just listening to all that noise," she says. Dozens of e-mails to officials didn't help. So Sherman went to see her doctor, who prescribed the most popular prescription sleep medication, zolpidem."