This article is from the Dreaming FAQ, by "Lars Rune Foleide" email@example.com .
Your body is paralyzed during REM, your body can't even stand (This is
why sleep walking happen in other stages of sleep). Sometimes does the
body fails to turn on your muscles immediately after REM. Normally
this condition lasts only a few seconds, but sometimes can it go on
for minutes, which causes a very scary feeling. But just remain calm,
it will pass. And it is not at all dangerous. You should also know
that sleep paralysis is great for leaving your body. Again, leaving
your body is not dangerous either.