"The bizarreness of it certainly sounds consistent with a side effect from these medications," said Dr. Michel Cramer Bornemann, a specialist at the Minnesota Regional Sleep Disorders Center.

"He has these other complicating medical conditions that would increase the possibility of complex nocturnal behavior."

Ambien, the hugely popular sleep aid that was prescribed to 26 million Americans last year, has been linked in some rare cases to extraordinary sleepwalking escapades.

Patients have reported driving, cooking, eating - even shoplifting - in their sleep. They generally don't remember doing it and have a hard time believing evidence that they did.

New York lawyer Susan Chana Lask filed a class-action lawsuit against drug maker Sanofi-Aventis in March, saying the pills are dangerous.

Among the plaintiffs are a Florida housewife who often ate raw eggs and whole loaves of bread while sleepwalking; a Texas woman who woke up in jail after driving while asleep and crashing into parked cars; a Navy lieutenant facing court-martial for shoplifting an "X-Files" DVD; and a New York woman who opened her door to a stranger while asleep and was sexually assaulted.

Cramer Bornemann said Ambien is generally very safe but problems can arise when patients mix it with other medications or have preexisting physical or mental problems.

Kennedy (D-R.I.) has battled depression and said he also took Phenergan, an anti-nausea medication that can boost the effect of sedatives like Ambien and is known to cause confusion.

Kennedy may also have taken pain pills - he said yesterday he was an addict - and that in addition to the cocktail would be a very bad idea, Cramer Bornemann said.

"If you're mixing narcotics with sedative hypnotics, you're mixing basically two depressants," he said. "You're compounding issues and there is increased risk of side effects."

Sanofi-Aventis notes the rare possibility of sleepwalking on the drug's label and says the drug is safe when used correctly. The company dismissed last month's series of media reports about weird side effects as "anecdotal."

Responding to the Kennedy case, a company spokeswoman noted that patients aren't supposed to drive after taking Ambien.

The drug maker just launched a big ad campaign to revive sales after prescriptions dropped 10% in March.

Originally published on May 6, 2006