Justin Bieber has revealed that at the height of his drug use his security team would check his pulse as he slept to check he was still breathing.

The 25-year-old singer admitted that at his lowest point he would wake up and immediately smoke cannabis and swallow pills.

Speaking in the latest episode of his YouTube series Justin Bieber: Seasons , the pop star said he first smoked cannabis when he was 13 and later became dependent on it.