Hi,
One of the problems with dreams is that the medical profession does not attach much importance to them.
Your dreams look after you while you sleep and wake you up when you had enough sleep. Your subconscious uses your past experiences, especially the unpleasant ones to wake you up. It also uses emotions of all sorts. Have you not heard the expression: "He/She got up from the wrong side of the bed"
Many times dreams set the mood of the day. It is normal.
If you are depressed or taking medicines, your dreams need to be more vivid and sometimes more violent to make you do the task your subconscious wants you to do.
My guess is that you had unhappy school times and your subconscious uses your negative past experiences to wake you up.
Try to regard your dreams as your guardian angels. Be they good or bad they're always trying to help you.