The 41 year old broke his back in monster truck crash in 2008 and was prescribed heavy medication during the months after the accident.
Grant confessed he wasn’t prepared for the affect the painkillers would have on him, and he had nightmares featuring his “deepest, darkest fears” every time he went to sleep.
“I could barely walk, so I had a dream and then I woke up, I believed we were in the middle of a home invasion … I’d go to fight off people that weren't there,” he said.
The Gold Logie winner said his hallucinations put his (then girlfriend) wife Chezzi Denyer “through the wringer,” with him once accusing her of going to London without him.
But the worst episodes came when the pain medication prompted him to go through an “escaping period”.
“I was down the street in my undies — this is Castlereagh Street in the city (in Sydney) — trying to find scotch, in my undies,” he said.