In the most recent installment of his Seasons YouTube documentary series, Justin Bieber details the extent of his former drug abuse.

During “The Dark Season” episode, Bieber confides, “People don't know how serious it got.” As a 13-year-old, the Canadian pop star says he was already addicted to pills and cannabis. “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.”

In a troubling admission, he described how members of his security team would have to check his pulse throughout the night to make sure he was still breathing."I was young, like everybody in the industry and people in the world who experiment and do normal, growing up things.” Unlike most teenagers, however, the stakes and opportunities for excess were greater. “I had a different level of exposure. I had a lot of money and a lot of things.”

His wife, Hailey Bieber, said she purposely didn't get involved in his life until he “chose to get sober.” Before they married, Bieber announced he was taking a break from music to work on his mental health. Since then he has opened up about his struggles with his mental health, and substance abuse.

Watch the episode trailer below.