rach, i don't know how you study but i'm going to presume a few things in order to give you this advice.
i'm assuming that you do not "cram" for exams. that said, the night before an exam, let it go. forget about it. take a bath, read a non-nursing book, do a manicure....whatever it takes to relax. you've probably already had a week or so of studying the material so take time to breathe the night before.
the morning of the exam, get up a little earlier than normal. if you are like me, i love to sleep and this is sometimes hard. :chuckle but i've found it works for me. get up, either fix some good light breakfast at home or stop for bacon and toast (my fav) on the way to school.
get there about 45 min. early and just scan your notes or note cards. do not do any indepth studying. you will get bogged down in the specifics instead of taking in the whole picture.
when you get your test paper, fill out all pertinent information and then BREATHE!!!!!!!!!! don't look at the first question until you have taken at least 3 good deep breaths. look at the ceiling and say to yourself "i can do this."
then do it.