More people are doing it to feel confident socialising - but what are the risks?
Related stories
'I've never seen anything like this' -- A U.S. doctor treats Ebola's youngest victims
Kids face a cliff edge in independence that can affect mental health
Campaigners hold vigil as stroke unit closes
Broccoli Sprouts Recall As Salmonella Outbreak Spreads to Four States
Humphries: Opening up on mental health was best choice I ever made
Medieval mental health