Of the several unusual things that I've had happed to me this was the first and probably the most terrifying. I was a young boy of about 4 to 6 years old. At the time this happened we had another family that was down on their luck staying with us. They had a son about my age and naturally we ended up sleeping in my bed facing opposite directions.
Before I continue I feel I need to elaborate on the bed I had at the time. The way the frame was constructed there was no under the bed. It was basically a box with dimensions slightly smaller than the mattress and had a mirror like surface. If one were to try and reach under the bed they would find this frame about 6 inches from the edge of the mattress on any side. This made it difficult to hide things under my bed when "cleaning" my room.
One night I woke up for who knows what reason. I was lying on my stomach and had my left arm hanging off the side of the bed (this would be the last time I ever slept with any part of my body over the edge of the mattress). I started to feel somewhat panicked and then something grabbed my hand from "under" the bed. My parents and grandparents always insisted it was the cat or dog but neither one of those animals can grab and squeeze like this creature could. I instantly yanked my hand up and sat up terrified, looking around and seeing nothing.
I noticed that the boy that was staying with us also had his hand off the edge of the mattress. I slowly crawled over and looked at his hand. There was a strange green light around it and these "things" that appeared to be flying around it. These were not fireflies because the things themselves weren't emitting the green light but neither was the boy's hand.
I didn't stay to investigate. I ran as fast as I could to my parents room where I found little comfort or understanding. To this day I don't believe this was a dream or my imagination. Whatever it was that grabbed my hand that night was as real and you or me. Also to this day I can't sleep with any part of my body of the edge of the mattress and I hate to walk by the bed in the dark because I know there could be something under it. Has anyone had anything like this happen? Even seeing the green light? It would be a relief to know I'm not alone.