Vibrations before sleep

Hi everyone..
I feel as if I am swinging before I fall asleep..My body beats like heart beatings.. I feel a prickling on my head around my crown chakra.. and I feel sudden shifts before I wake up.. As if I jump from one place to another one..
I also have a dream in which I wake up but I can't move and I can't get out of my bed.. I have this dream very often and when I finally wake up I feel too tired and afraid..
A friend told me that it was called sleep paraylsis and can be used for astral journeys.. but I don't know how to do it and also I am really afraid of it.
Do you experince things like that? and if you do what do you do at those moments when you can't wake up in your dream?
Love and light..
Arzu..