I've had this since my late teens. It's more common when you have irregular sleep patterns. Nowadays it's more rare.

It's scary shit, specially if you panic. In time I've learned to control it when I have an episode and mostly succeed. But occasionally I still panic, but not like before.

Wiggling a toe will make the movement come back slowly and if you recognize what's happening and keep calm you'll avoid the most disturbing hallucinations. You can even succeed in controlled lucid dreaming during an episode.

I never saw the demon but I have felt its presence. It's actually not as scary as it sounds. The scariest hallucinations were actually feeling people had entered my room and were intending to hurt me and I couldn't budge. Once it happened with my old landlord when I was in college. He lived upstairs and I had an episode after falling asleep in my living room. I heard him enter my unit and saw him stand over me talking gibberish. It was so unsettling. I finally moved in a panic and I was by myself. He was actually a very chill guy, best landlord ever.

A few times I was unable to move, alone in the dark, and suddenly moved unexpectedly only to see my girlfriend or room mate towering over me and tell me I was moaning heavily in my sleep and thought I was having a bad nightmare. I've wondered how many of the sleep paralysis are actually nightmares and we ARE asleep.