4 years of study groups that go until 3 am will do that to you.
I'd put my kids to bed at 8, and I'd sleep until 1-2 am, then get up and study til the morning. I'll tell you, I don't know how I did it, but I did. Graduation was on mother's day, it was one of the best moments of my life.
Well, the beer and peanuts helped!