I took an afternoon nap, usually i cant fall asleep very well. anyways i was just sitting completely still on my back. I mean laying on my back and i was listening to the "Ultimate lucid dream induction" mp3. Just looping it. And i was just counting Suddenly after about 20 minutes my heart started to beat extremely fast and i could feel something like in my head. It felt like a heart attack. Is this normal Sleep paralysis before a LD. ive never LD'd b4.