i will offer advice. feel free to do with it what you will.
1. BREATHE!!!!!! people have heard this response from me before so i'm sure it is getting old. but it's oh so true. just stop everything you are doing and breathe. focus on breathing in and then out.
2. PRIORITIZE. i know it's hard to keep from thinking about the things you have already turned in, but let it go. you don't have time to dwell on it. think instead about being confident in what you have finished. you wouldn't knowingly turn in less than your best, right? so if it comes back with good marks, know you did well. if it doesn't, then consider it a learning experience. so let it go for now. it's too late to do anything about it.
then ask yourself, "what is the next thing that must be done?"
do you need to complete an assignment for the next day? if so, finish it. and when you finish it, let it go. you can only polish so much before you wear the finish off of anything. do your best then move on to the next thing.
do you have an exam coming up next week? then look over the material. don't do intensive studying. remember, you can't cram nursing into your head. review every day even if it's only for 10-15 minutes.
3. SLEEP. if your body is telling you that you've had enough, you may as well listen. you are doing yourself and your learning experience a disservice by denying yourself at least minimal sleep. now i'm an 8 hour a night girl myself. and i know that 8 hours isn't always possible. but at least nap if you can't get a full night's sleep. maybe look at the times you are sleeping/studying? could you adjust your lifestyle so that you sleep in the early evening and maybe get up super early to study?
4. EAT. anyone remember in A & P, that the brain needs carbohydrates to function? you gotta get something in you other than popcorn, candy bars, and chips. (although these are my personal favs. :chuckle)
of course, these aren't cure-alls especially since i'm not entirely in your shoes. but being a student nurse is one tough job. but try and relax and take everything one day at a time.
best of luck!