Are you a morning person or a night owl?
I am without a doubt a night owl. When I'm not working, I usually go to bed at 4 am, no joke. During undergrad, I would start on homework at midnight. I just work best at night, I suppose. I don't think I'll be like that in graduate school, simply because I have class at night and each class only once a week, giving me a lot more time to work on things.
I have never been a morning person. I'm not even worth talking to before 10 am, even if I'm at work. I can wake up if need be, but if there is no reason to get up then I am just capable of sleeping and/or being lazy until 2 or 3 in the afternoon. It's quite a gift, let me tell you. ;)