Apparently I have had a much easier time than many of the above posters, as I commuted 40-60 minutes each way to every third year rotation and have experienced no impairment to my performance, driving safety, or mental state.
I probably wake up half an hour earlier than my classmates who live closer to the hospital, but get roughly the same sleep. If anything, the time cuts into extracurricular activities/social time much more than it does into vital study/sleep time. To make the most o fit, I listen to educational podcasts 80% of the time to get some review in and make studying quicker when I get home.
FWIW, some of the anecdotes here illustrate worst-case-scenarios of people with long commutes who may have not managed it as well as possible - there are likely dozens of your classmates, faculty, and even residents you have shared/will share rotations with who manage a similar commute with no ill side-effects, and you would never tell the difference because they manage their time well. No need to despair.