Tweak pretty much summed it up for you juroara


SP
Sleep paralysis
Sleep paralysis consists of a period of inability to perform voluntary movements either at sleep onset (called hypnagogic or predominately form) or upon awakening (called hypnopompic or postdormtal form).
Sleep paralysis may also be referred to as isolated sleep paralysis, familial sleep paralysis, hypnagogic or hypnopompic paralysis, periodontal or postdormital paralysis
What are the symptoms?
More information @ http://watarts.uwaterloo.ca/~acheyne/S_P.html (Nesgirll_119)
|Tutorial|

It is nothing to be afraid of.
It seems as though your mind wants to rest but you get stuck in this in between stage.
It is a natural function for your mind to stop motor functions while you asleep. This way you won't be flailing around in your sleep. Some times this message is slow getting there. And hence, SP.

There is a link to insomnia issues in the Tutorials also.