OLD HAG SYNDROME is a phenomenon in which you awake from sleep unable to move. You seem to be awake, but your body is paralyzed. As if this wasn't scary enough, these episodes are often accompanied by a feeling of an unknown presence in the room, strange sounds, and other mysterious manifestations. In the classic experience, the victim feels that an old woman in sitting on his chest, rendering him immobile and laboring to breathe.
To the medical world, the phenomenon is known as sleep paralysis combined with hypnopompic hallucinations. Those who experience the syndrome, however, are not easily convinced that what they see, hear, and feel are not real. And how can we explain when two or more people experience the phenomenon at the same time?
Here are some of the scariest old had experiences readers have reported.
source @ http://paranormal.about.com/od/humanmyst...iences.htm