July 15, 2012 -- New questions are being raised about the sleeping pill Ambien after Kerry Kennedy, the ex-wife of New York Governor Andrew Cuomo, may have been under the influence of the sleeping aid when she was involved in a crash with a tractor-trailer on a New York highway and left the scene.
Kennedy was arrested and charged with driving while impaired Friday. She is due in court Tuesday.
ABC News has learned that Kennedy told police she may have taken Ambien sometime Friday morning, but doesn't remember for sure. But her family said in a statement released to ABC News that there were no drugs involved.
"Kerry Kennedy voluntarily took breathalyzer, blood and urine tests -- all of which showed no drugs or alcohol whatsoever in her system. The charges were filed before the test results were available," the Kennedy family said in a statement released Friday.
The results of Kennedy's toxicology tests are still pending. But legal analysts say whatever they show could play a big role in her defense.
"Ambien has a short half life, so by the time she went to the hospital and by the time her blood was analyzed, the drug actually could have disappeared from her system," criminal defense attorney Dana Cole said.
There have been previous complaints about Ambien lulling people into trance-like state.
Last year, 60 million Americans were prescribed a sleeping aid.
But for a drug that's supposed to help you sleep, it's amazing how active you can be and not know it.
There are numerous claims of "sleep driving" by people who took the drug.
A woman learned she was "sleep cooking" and even fried an egg, while another woman woke up and found out she wasn't even home.
Kerry Kennedy's cousin, former Rhode Island Rep. Patrick Kennedy crashed into a barrier near Capitol Hill, saying he had been disoriented after taking Ambien.
The details of Friday's accident don't fit Kennedy's public image -- a mother of three who has no known history of substance abuse.
"I seriously doubt that she'll be looking at any jail. She's looking at a fine and probably some sort of drug or alcohol program that she'll need to attend," Cole said.
ABC News' Richard Esposito contributed to this report.