An interesting article was published on the NY Times last month:
Medical Student Burnout and the Challenge to Patient Care
I admit that I've experienced burnout. If medical students experience such extreme burnout and even thoughts of suicide (see this article from the Annals of Internal Medicine about suicidal ideation among US medical students), then imagine what residents go through? Medical students don't have the same type of responsibility that interns and residents experience. Burnout after training also causes many practicing physicians to leave medicine and pursue a non-clinical career.