Since then, Dr. Silber said he had seen other Ambien users with sleep-related eating disorder.

"This is really an upsetting thing for them to see what they're doing during the night," he said. "They put on weight. I could imagine setting fire to things" while preparing food.

Among sleep-eaters, the desire for food can be tremendously powerful. One woman in the Minneapolis area whom Dr. Schenck treated, Judie Evans, said she began taking Ambien while recovering from back surgery. At the time, she was in a full body cast and needed assistance to get out of bed.

During this time, Ms. Evans, who is 59 and lives alone, began to notice that food was missing from her refrigerator. She accused two nursing aides who were caring for her of stealing food. It was not until her son came to spend several nights that Ms. Evans said she realized that despite the body cast, she was getting up to eat while she was asleep. "During the day, I couldn't even make it to the bathroom by myself," Ms. Evans said.

The first night her son was there, he found her standing in the kitchen, body cast and all, frying bacon and eggs. The next night he found her eating a sandwich, Ms. Evans said, and sent her back to bed. Later that same night, her son arose to find her standing in the kitchen again. "I had turned the oven on," she recalled. "I store pots and pans in the oven and I had turned it to 500 degrees."

Ms. Evans said her problems ended when Dr. Schenck diagnosed Ambien-induced sleep-related eating disorder.

Another woman who has complained about sleep-eating was Helen Cary, a labor and delivery nurse in Dickson, Tenn., who began taking the drug so she could sleep days while working 12-hour night shifts.

"I'm very ambivalent about this drug," said Ms. Cary, 57. "Without it, I would never have survived five years of night shift." But Ms. Cary said her behavior became strange while under Ambien's influence.