I had one once when I was camping out in a field outside of a small town. It was in late fall and the rain was starting to come down pretty bad so I looked for a secluded spot and setup my pup tent. I was about 21 I guess. After drifting off to sleep I was awaken by a dark figure setting on my chest. I struggled for what seemed like forever but in reality it probably was less than a few seconds. My eyes were open and I could see this strange shadow getting off of me and drifting through my tent wall.

It happened over 30 years ago and it still makes my skin craw when I recall it.