Figures released this morning show an increase of almost a third in the number of calls made to the St Patrick's Mental Health Support Line Service last year.
Calls to the service increased by 29%, while there was a 46% rise in email inquiries.
There were almost three times more calls from women than men.
It was the busiest year yet for the service, which is now in its fifth year.
The agency said the increase in calls about adolescent mental health was "a real area of concern".
Chief Executive Paul Gilligan said recent research had suggested that more Irish young people suffer from mental health difficulties than their European counterparts.
He said that while this was "concerning", it was positive that people were seeking information.
The service can be contacted on 01-2493333 or via email at email@example.com