Adam Richard Chapman was exhausted and had slept for only a couple of hours in the days before the February 11 attack, according to evidence before the court.

The 36-year-old's erratic behaviour was also attributed to the mental health problems he suffered, including bipolar and post-traumatic stress disorders.

Considering Chapman's lack of planning or finesse in executing the crime, Judge Paul Conlon agreed that he was not thinking clearly at the time. "His head didn't seem to be on his shoulders," he said.

The bumbling bandit gave little thought to a getaway when he rode his bicycle to the Westpac branch at Shellharbour City Centre about 2.30pm that day.

Dressed in distinctive clothing and carrying a backpack, he entered the bank and filled out a withdrawal slip in the name of Billy the Kid before approaching a teller.

He demanded cash from the woman and showed her what looked to be a toy gun in his backpack before producing a knife.

The teller, who immediately activated a security camera, gave Chapman $5000 cash before he fled the bank, leaving his knife and bicycle at the scene.

He then caught a taxi to his home in Brookfield Place, Warilla, where investigating police found him the next day.

Yesterday the court heard Chapman stopped offending between 1998 and 2009.

Reports from his psychiatrist and a mental health support worker said Chapman could function with counselling and medication.

Judge Paul Conlon convicted Chapman but took his obvious remorse and well-documented mental health issues into consideration.

He ordered that Chapman, who has been in custody since his arrest, be released on parole on June 11 next year.