i have been trying to ge a answer to this for many years, and i still do no have one. this does not happen everynight. but when it does it is very scarey. when i lay down to go to sleep and just when i feel like im going to sleep i get really dizzy and feel like im blacking out. this conttinues everytime i get close to going to sleep.i change postions and it doesnt help. it keeps doing it until i finally just stop fighting it and fall asleep. the last doctor i told this to, just said you have got me stumped, i have no idea what is causing this.