Liam Payne "went off the rails" and drank too much after One Direction split.
The 26-year-old singer sought therapy after the group went their separate ways in 2015 because he was struggling to figure out who he was and function without the tightly-controlled confines of the 'History' band.
He said: "I went into therapy a couple of years after leaving. I kind of went off the rails a little bit and just couldn't really figure out what was making me sad. So, you know, my team got somebody around to help me through a couple of different, difficult things that I was going through.
"I was just trying to figure myself out. It was just such a strange course through life, and then when the switch turns off you're left to your own devices."
During his low period, Liam - who has two-year-old son Bear with former partner Cheryl - admitted he got into a lot of "bad situations" because his drinking got out of control as he sought to escape his "crazy world".
He told GQ Hype magazine: "There was a lot of stuff. I was drinking too much and getting into really bad, bad situations for quite some time actually.
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"And I hit a peak moment where I knew the drinking was going to get me; I needed to do something about it.
"I spent a lot of time drinking to escape the crazy world that I had created for myself. I didn't know what I was doing.
"That first therapy session and being like, 'I don't even know what I like or anything about myself' - it was pretty scary stuff. I was afraid of how far my career was going and that it might go even further.
"You can say, 'Who is afraid of success?' But that's what it entails sometimes. Success has got the better of me on more than one occasion. When I am losing I tend to concentrate more."
The 'Strip That Down' hitmaker gave up alcohol for a year but isn't convinced it made his life any "better" as he missed out on so much socially, so he's still trying to find a balance.
He said: "I got sober for about a year, cutting down so the only vice was cigarettes.
"I hadn't planned to go sober forever, it was more important for me to say I didn't actually didn't need to drink. I wanted to prove it.
"I did the whole year, no booze completely, and at that point I didn't actually know being sober was making my life any better.
"Things went up, but things like my social life plummeted. I was the biggest recluse on the planet. I would get up at 5am and go running in the park, but at night I would be in bed by 7pm. Is that a way to live your life?
"And in a strange way I am trying to still figure all that out and get the balance right between being a party animal and being an animal in the gym - the latter not being fun at all. We are all at fault; we all need balance."