I have fears too when I start a new job or internship. It was recommended to me once to put all the fears on paper, so on the left side of a page write all of the concerns down to get them out of my head. Then on the right side, put beside the worries what can be done to counteract them - ask, "is this a fact that it is really something I should be concerned about (?)" and if so, to put down a plan to head them off and "what can I do to prevent it?" Such as being concerned about the sleep patterns being affected, then making sure you combat the stress with diet, exercise, and bedtime routines which are all conducive for this. I put this then where I can reference it, fridge, bathroom, etc. Having a plan usually helps to fight off the concerns.

I try to think of it as an adventure: the joy of the work in the field I am interested, new people and experiences to share, experience for future work, valuable personal and professional insight, and the chance to try something I never have before. You have the schooling now and the opportunity to use it; see what fun you can have with the new people and the work you will be doing and take it one day at a time, one moment at a time. You can do it! Good luck!