The incident reported from New South Wales' Maroubra city at around 2 AM local time when Katie woke up to find the 25-year-old stranger sleeping in bed next to her and her partner.
When challenged by her partner Chris, the alleged intruder picked up his clothes and went to leave the home. Police was called in as her partner attempted to shut the intruder in their back yard.
The Irishman, in an attempt to flee, then climbed through the kitchen window and began wandering around the home until police arrived and arrested him.
The Irishman, who faces aggravated break and enter charges, will undergo medical and mental health checks at a nearby hospital for possible drug related health issues.
The couple believe he got in through a window that they keep slightly ajar for their cat.