'Bieber saved himself from damage by cancelling tour'

"When someone pulls remaining dates of a tour, it means they would have done real damage to themselves if they kept going. We've lost so many great artistes lately. I give Justin (two thumbs-up emojis) for realising it was time to call it."

"You should too," Mayer tweeted. Angelakos, who has been candid about his struggle with bipolar I disorder, retweeted Mayer's posts, and also offered his own take on the intersection between touring and mental health.

"'Mental health reasons' went over REALLY well when I had to cancel shows five years ago (in a hospital receiving electroconvulsive therapy).

"Was pretty rough but then my doctors and I worked out a relatively manageable balance between treatment and touring. Toured for over two years," Angelakos tweeted.

The statement announcing Bieber's tour cancellation did not reveal an exact reason, though it did attribute the decision to "unforeseen circumstances." Justin Bieber has performed more than 150 shows in 40 countries across six continents and 16 months on his world tour.