OP you will have to get used to it. The world for doctors gets started around 7 AM for most fields, 5 AM for surgery. Lots of family med people I knew usually got in around 730 AM to get ready for the day, first patient normally 8 AM. There are fields that you can do night work but that's not advantageous to stay up all night and sleep all day. I'd advise looking for something with a later morning start. Psych usually is later morning, 9 AM or so. EM maybe depending on the shift. Anesthesia gets started early (630-7 am) but also get done early (at my main hosp usually 3-4 pm).
I too am not a morning person but that's mainly because I stay up too late. So my advice is to start going to bed earlier now. I am normally still up at midnight, despite having to wake up at 5 AM normally, and know that can't be normal... because it isn't. Makes 3rd year very hard even on easier rotations. Get between 7-8 hours each night and you'll be good. Once you get going in the morning it's not too bad, it's really when you get home in the evening around 5-6 and then it hits you.