Ignore everything around you and just focus on your school work as best you can. I know that getting along with everyone makes you feel comfortable, but you're main goal is to build your education. Don't forget that. Its of course fine to have your friends and get along, but don't let it be a distraction.
To manage your stress and anxiety, there are a couple things you can do. Make sure you're eating properly and staying hydrated. Practice slow, deep breathing. Do some exercises, doesn't matter when, and your brain will release chemicals that will help aid you in feeling better. School comes first, but make time for fun and social interaction. Get a hobby to keep you busy.
For sleep, that's a little more difficult. Don't eat anything too close your bedtime, especially things like ice cream. Stay off of your electronics an hour before as well. Stick to things like reading or drawing or something. If you feel like you need someone with you, try getting a big stuffed animal.