Comment by hermitcrab

"People who experience sleep paralysis sometimes hallucinate a demon-like creature sitting on their chest"

Interestingly, the experience of sleep paralysis seems to change with the culture. Previously, people experienced it as being ridden by a night hag or some other malevolent supernatural being. More recently, it might account for many supposed alien abductions.

The experience of sleep paralysis sometimes seems to have a sexual element, which might also explain the supposed 'probings'!