Justin Bieber has revealed he once feared he would die from drug abuse, saying members of his security team would be on alert to check his pulse and breathing throughout the night.
Speaking in the latest episode of his YouTube series, the 25-year-old star talks candidly about bingeing on ecstasy and hallucinogenic mushrooms, and said that at his lowest point he would smoke cannabis and swallow pills as soon as he woke up.
It is not the first time Bieber has spoken out about his issues, admitting to making "bad decisions" when he was younger in a social media post in September 2019.
In his YouTube show, Justin Bieber : Seasons, the singer has opened up further, saying he became dependent on cannabis after starting smoking the drug at the age of 13, and that harder drugs followed as he struggled to cope with the pressures of fame.
He also admitted to drinking the cough syrup and soft drink combination known as "lean", which is popular among many rappers.
Bieber said taking drugs provided an "escape" from his life.
"I was young, like everybody in the industry and people in the world who experiment and do normal, growing up things," he said.
"But my experience was in front of cameras and I had a different level of exposure. I had a lot of money and a lot of things."
Bieber said he decided to get clean because he feared the drug use was about to kill him.
"People don't know how serious it got," he said. "It was legit crazy scary.
"I was waking up in the morning and the first thing I was doing is popping pills and smoking a blunt and starting my day. So it just got scary."
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Bieber was discovered on YouTube by talent manager Scooter Braun when he was just 13, and went on to have global success with hits such as Baby and Boyfriend when he was still in his teens.
There was a period when the star was making headlines for his controversial behaviour just as much as his music, and in 2014, a petition demanding he be deported from the US attracted more than 100,000 signatures.
He has infamously had several brushes with the law, including allegations of vandalism, assault and driving under the influence.
The singer's wife, model Hailey Bieber , also appears in the documentary and said she chose not to get involved in his life until he "chose to get sober".
The couple married in a low-key ceremony in 2018, followed by more lavish celebrations last year.
While Bieber has previously spoken about his struggles with anxiety and depression, he has now given fans an inside look at how he treats the illnesses, relying on an oxygen chamber to relieve stress.
He also works closely with brain disorder specialist Dr Daniel Amen, who features in the latest episode of Seasons.