The death of a beloved aunt combined with Green Day's crazy schedule sent punk star Billie Joe Armstrong spiralling into a drug and booze haze.

The American Idiot rocker recently emerged from a rehab stint and announced plans to return to the road with his band, rescheduling dates the group was forced to scrap last year (12) following his meltdown onstage at the iHeartRadio festival in Las Vegas - and now he is recalling the events that led to his fall.

He explains, "I found out my aunt had passed away. I had to go back home. I helped my cousin pay for the funeral. My aunt - my mom's sister - was a big presence in my family. That hit me pretty hard.

"Then I started getting overwhelmed. We (Green Day) were doing press every day. There was the tour. We were thinking of another tour after that. I was overbooked and exhausted."

Armstrong started taking pills for anxiety and to help him sleep, but adds, "I started combining them to a point where I didn't know what I was taking during the day and what I was taking at night. It was just this routine. My backpack sounded like a giant baby rattle."

His substance abuse almost led to the group cancelling a string of European shows last summer (12), when Green Day's manager realised Armstrong was in trouble.

The singer recalls, "I get a text from my manager: 'Come on down, we have to talk about the Reading Festival'. I went down there... and he goes, 'We're getting on a plane. We're cancelling the rest of this tour, and you're going to rehab.' I was like, 'What the f**k are you talking about? I'm not going to do that.'

"We got to this theatre gig we were playing in London. I said, 'I don't want to cancel these gigs. It just can't happen. Tell you what, as soon as we get home, when we're done with the press and stuff, after iHeartRadio, the week following I'll go to rehab, but I can't cancel any of this s**t now.'

"It turned out I was a week ahead of schedule."

Armstrong checked into rehab the day after his Las Vegas meltdown at the iHeartRadio festival.