The pop star, 25, said he would smoke weed and pop pills as soon as he woke up.
He told how he was dependent on marijuana at 13 – and later took other drugs including a codeine-based cocktail plus MDMA and mushrooms.
The Canadian superstar said: “My security were coming in at night to check my pulse.
“People don’t know how serious it got.
“It was legit crazy, scary.”
Bieber said he stopped as he feared he would die.
His doctor Daniel Amen says “he was a wreck” when he first met the star in 2014.
He added on the YouTube documentary: “Anti-depressants help me get out of bed.”
Bieber’s recovery routine now includes a hyperbaric chamber and endures IV infusions to rid his body of toxins following years of drug abuse.
The 25-year-old singer explained that he had been “struggling with a lot of anxiety” as he climbed into his own personal chamber during the 14-minute video.
“I’ve abused my body in the past and now I’m just in the recovery process trying to make sure I’m taking care of my body and taking care of the vessel that God’s given me,” he said.
In the documentary, Bieber explained how the hyperbaric chamber worked.
“It fills up with oxygen,’ he said. I really have been struggling with a lot of anxiety. You get more oxygen to your brain so it decreases your stress levels. It’s pretty cool.”
Bieber’s wife, Hailey, admitted that the couple has various chambers available for the singer to use at their house and in the studio.
“People are going to think he is a crazy person,” she said. “People are going to be like, ‘What is this contraption machine, that’s some rich people s**t.’
“Mental health is so important to get on top of,” Bieber added. “If you have ADHD if you have … something and you don’t want to take medicine, I strongly believe in it.”
The episode also documents him being diagnosed with Lyme disease after he was mistakenly told he was bipolar.
He said: “It feels good to now know why I felt so crappy all this time.”
Hailey Bieber added: “He just felt so sick and there was no explanation for what was going on.”