There has been a sharp rise in the number of days junior doctors in London were signed-off with stress, anxiety and depression, the BBC has learned.
Days lost through these absences have risen by 159% since 2011, figures from 21 London hospital trusts show.
Unfilled rotas means more pressure on the remaining staff, the chair of the BMA Junior Doctors Committee Dr Johann Malawana said.
NHS Employers said more specialist help was now available.
"Nonetheless we cannot be complacent as progress is uneven and more action is required," chief executive Danny Mortimer said.
Across 21 London hospital trusts about 1,200 days were lost through junior doctors being signed off for mental health issues in 2011 compared to about 3,180 in 2015.
The BBC is awaiting the full results of a national Freedom of Information Request about junior doctors' days lost in England and Wales.
The Practitioner's Health Programme, (PHP) which offers support and counselling to NHS doctors in London, said demand was so high at one point last year that it was forced to close its doors for six weeks to catch up with the level of referrals.
Dr Clare Gerada, who runs the service said: "I've worked in the NHS for 35 years and I have never seen so many demoralised individuals."