The bassist tried to kill himself by sitting in a fume-filled car in February, 2011 after sinking into a low following the breakdown of his relationship with The Saturdays singer Frankie Sandford.
He then spent more than a month in Britain's The Priory clinic to receive treatment for depression and substance abuse, and has since recovered and remained fully sober.
According to Britain's Daily Mirror, Poynter opened up about his suicide bid in an interview on U.K. talk show Alan Carr: Chatty Man, as he and his bandmates promoted their new autobiography, Unsaid Things... Our Story.
Host Carr told Poynter he was shocked by the revelation, insisting, "Listen, I have got to say, it got really dark, about you trying to kill yourself..."
The musician replied, "Yeah," before adding, "It's always good to reflect on that sort of stuff. I'm in a really, really good place now. It is quite easy to forget. It's quite therapeutic to go back, quite scary and a bit of an eye opener into how dark it can get if you take your foot off the gas and stop looking after yourself."
Bandmate Harry Judd told him, "Half the time you didn't know what you were doing - it was us telling you," to which Poynter replied, "Yes, because I was so battered (drunk)."
Frontman Tom Fletcher said, "We are all in good places now. Dougie has sorted himself out and I am married."
The band's full interview will air in the U.K. on Friday (12Oct12).