Prof. Sheehan was appointed as a Consultant in Liaison Psychiatry at the Mater Misericordiae University Hospital in 1995. It was the first official Consultant in Liaison Psychiatry post in Ireland. He was also appointed to the Rotunda Hospital, Dublin as a Perinatal Psychiatrist. He trained in Ireland, Zambia and at Guy’s Hospital, London where he worked as a Consultant Psychiatrist. He is a Member of the College of Psychiatrists of Ireland, a Member of the Royal College of Psychiatrists and a Fellow of the Royal College of Physicians of Ireland. He has a Masters of Medical Science in Psychotherapy. In 2016, he was appointed UCD Associate Clinical Professor in the UCD School of Medicine.
He has a specific interest in medical education and is the Convenor of the Diploma in Psychiatry examination which is awarded by the Royal College of Physicians in Ireland and the Royal College of Surgeons in Ireland. He has served as the Chair of the Liaison Psychiatry Section of the Irish College of Psychiatrists and for ten years was the Irish representative on the Executive of the Liaison Psychiatry Section of the Royal College of Psychiatrists. His research interests include depression in the medically ill, somatoform disorders, alcohol use disorders and Perinatal Psychiatry.