Miley Cyrus is glad she has made it to 28 because she feared she'd join the likes of Amy Winehouse and Janis Joplin in music's most tragic club.

Winehouse and Joplin - like Brian Jones, Jimi Hendrix, Jim Morrison, and Kurt Cobain - died at 27, and Miley reveals she quit drugs and alcohol earlier this year to help make sure she didn't join the 27 Club.

"27 to me was a year that I really had to protect myself," she said to Apple Music's New Music Daily. "That actually really made me want to get sober because we've lost so many icons at 27. It's a very pivotal time.

"You go into that next chapter or this is it for you. I just feel that some of the artists that almost couldn't handle their own power and their own energy and their own force... It's an energy."

But staying sober hasn't been easy, and Miley, who celebrated her 28th birthday on Monday, admits she slipped up earlier this month.

"I would never sit here and go, 'I've been f**king sober'... I fell off and I realised that I now am back on sobriety, two weeks sober, and I feel like I really accepted that time," Miley shared. "One of the things I've used is, 'Don't get furious, get curious'. So don't be mad at yourself, but ask yourself, 'What happened?'

"To me, it was a f-up because I'm not a moderation person, and I don't think that everyone has to be f**king sober. I think everyone has to do what is best for them. I don't have a problem with drinking. I have a problem with the decisions I make once I go past that level of... I've just been wanting to wake up 100 per cent of the time."

But she's determined to stay away from her vices throughout the U.S. holiday period.

"I'm very disciplined," she continued. "It's pretty easy for me to be sober or in and out of sobriety because it's like the day I don't want to f**king do it anymore, I don't. The day that I do, I do. You know? But when I don't want to it just is. I'm just very disciplined."