Bradley Cooper was once so drunk he deliberately banged his head on a concrete floor to prove how tough he was.

The 'Hangover' actor used to regularly drink alcohol and take drugs but realised he had a problem when he deliberately harmed himself just to show people he was "tough".

He told the Hollywood Reporter: "I was at a party, and deliberately bashed my head on the concrete floor. Like, 'Hey, look how tough I am!'

"I did it again. And I spent the night at St. Vincent's Hospital with a sock of ice, waiting for them to stitch me up."

Following those incidents, Bradley decided to completely quit drugs and alcohol eight years ago and says it was a turning point for him.

He added: "I don't drink or do drugs anymore. Being sober helps a great deal... I remember looking at my life, my apartment, my dogs [when I was still using], and I thought, 'What's happening?'

"I was so concerned what you thought of me, how I how I was coming across, how I would survive the day.

"I always felt like an outsider. I just lived in my head. I realised I wasn't going to live up to my potential, and that scared the hell out of me. I thought, 'Wow, I'm actually gonna ruin my life. I'm really gonna ruin it.'"