Justin Bieber relies on a massage technique to relieve stress

The singer's health coach told 'Justin Bieber: Seasons': "Justin and I developed a routine, in when he feels stressed, that he can use a technique called Havening I was trained in."

The technique involves massaging the singer's temples and face whilst he's sat in a hunched-over position.

Dr. Mingin explained: "Havening is a psychosensory technique that actually raises the feel-good chemicals in your brain on demand."

According to the expert, the technique lets Justin "know what it is he should be doing in the moment he's feeling stressed".

The duo actually have a "co-ordinated signal" that lets Dr. Mingin "know what's wrong, how he feels, and what he needs".

Meanwhile, Michael Ratner, the director of 'Justin Bieber: Seasons', recently admitted the pop star finds his documentary series "uncomfortable" to watch.

Speaking about one episode, in which Justin details his past drug use and health struggles, Michael explained: "Once we watched episode five together and he was just staring at it and he said, 'This is tough ... There's power in weakness.'

"I thought when he said that, he said, 'The very reason why it's sometimes uncomfortable for me to watch, that is the reason I want it out there.'"

Michael and Justin watched all the episodes together before they were finalised, and the director said they had "deep conversations about why things were a certain way".

He added: "It was never a place of subjectivity or trying to make a Justin Bieber commercial. He was never trying to use this as a vehicle to push album sales. It was really about how to tell [his] story."