A Wollongong man who used power of attorney to fleece his father out of more than $157,000 in life savings will spend at least a year behind bars.

Shane Williams was debilitated by anxiety, depression and alcoholism when he signed power of attorney documents at a January 14, 2014 meeting at a Wollongong solicitor's office, the Illawarra Mercury reported.

The papers named Williams' 27-year-old son Toby Di Comun Williams as the principal. They required him to keep his own money and property separate from his father's, to act honestly and not to gain a benefit from his position unless authorised.

Instead, Di Comun Williams sealed his father's financial ruin with a year of indulgent spending on holidays to Japan, Melbourne, Cairns and Port Douglas, hotel stays, a skydiving jaunt, car repayments and a deposit on a brand new car for his partner.

He opened new accounts to aid the deceit and used credit cards in his father's name to make thousands of dollars in purchases. In all, he transferred $44,089.83 directly into accounts in his own name. He used another $26,777.98 to pay a car debt for himself and his partner. Another $86,572.31 went in transactions from savings, credit card transactions and incurred debt left on credit cards in his father's name.