I read a story from deepak22 about sleep paralysis and I think even I have one experience bit similar. But I'm still not able to find out if it was a scientific or paranormal event.
This was during my early working days and I was 23. I had just finished my night shift at a manufacturing unit and came home and slept at around 10 AM. I was alone at home and I immediately went to sleep. But at about 11 AM, I woke up and see myself sleeping head down. As I open my eyes, I am able to see everything at home as normal and same as it was at the time I slept. But the most strange part was, I was unable to lift my hand and get up. I could feel the force of a palm with 5 fingers on my head and it was pushing my head down. I tried my level best to turn my head or lift it up to see who was behind me and was pushing my head. But I was hardly able to see it. But even in this mysterious situation, there was a sense of safety in myself and I was somehow confident that whoever it might be, won't be hurting me to any extent.
After some sort of struggle I finally gave up the idea of lifting my head and I don't know how, I just went back to sleep and I woke up again after 2 hours and was continuously thinking if it was a dream or it happened in reality.
I cannot accept it as a dream because, usually when I dream, I never see the surroundings so clear and in place as it normally would be. It will be usually a different place or unclear surroundings in our dream. But this thought still keeps me thinking about it even after 12 years now. But I never experienced such a thing again.