[Solumina]

It happens when your body doesn't fall asleep properly, you body releases a chemical that semi-paralyzes you so that you can't act out your dreams, this is supposed to be released during the second stage of sleep but if your body is under stress it can release the chemical during the first stage (where you are still semiconscious), stress can also cause your body to release too much (won't kill you but can make breathing feel labored) or too little (like in the case of sleep walkers).

On another note: homemade toaster pastries are yummy