sleep paralysis

[SpaceFlower]

does anyone know what the body Physically does to stay paralyzed during sleep? I've had problems on several occasions where I finally get lucid and then while trying to do things in a dream I end up doing them with my physical body. -tried rubbing my hands to stabalize a dream and actually woke myself up. -Wanted to freak out a dream character by sticking my head through a fish tank and blowing bubbles. When I took a deep breath underwater i actually did it. Then when I pushed my lips out to blow the bubbles I physically did that as well ending my dream. -tried to run really fast and kicked my legs in bed. I'd imagine the brain must produce some sort of chemical during sleep to keep your body still. Is there any kind of food or supplemenet I can try?