Dreams and anxiety, two pieces of the mind joining together while we are asleep. Many times we have nice dreams while at other times you have stress dreams. You arrived at school with no clothes on or the classic Waiter dream where you cant get to all the tables.
There is a study that sites that stress dreams are actually good for you because it is a dry run on the worst case scenario. So your brain is actually trying to make sure you know that you are able to do all the different tasks you have to do and you will be quiet all right.