Attorney Nicholas D'Amato told a judge Wednesday that he plans to use a medical defense for Winston Riley based on that claim, the Norwich Bulletin reported in Thursday's editions.
The Bridgeport man was arrested on March 18 after the woman told police he had flashed a large knife and tried to grab her purse while the two were alone in a parking garage elevator, police said.
Riley said he was awakened by the woman when she ran away in confusion and fright, D'Amato said.
The lawyer said he's confirmed with Riley's family that the 27-year-old has had a problem with sleepwalking since he was a child. The lawyer said he's in the early stages of gathering medical records in his attempt to convince prosecutors they should take the claim seriously.
"It is the first time we've encountered this," D'Amato said. "This is a legitimate medical condition."
Riley's bond was lowered Wednesday to $85,000 from $100,000. He is due back in court July 17.
Police said Riley confessed to the crime after he was arrested and told them he "just wanted some money."
D'Amato said the facts don't add up, since his client has no criminal record and is married.
"I told the judge and prosecutor... `Do you honestly think he woke up one morning, drove across the state and decided to rob a woman in a place full of security cameras?"' D'Amato told the newspaper. "It doesn't make sense if you think about it rationally."