ddobson on 31 May 2007
There's an established phenomenon that can occur when you're on the edge between being awake and asleep. The visual receptors "invent" images that the brain interprets further as being a figure or a shape, and the person is not conscious of being asleep. Whenever someone brings up one of these experiences, that's usually the first question -- were you tired or asleep? It's often accompanied by "sleep paralysis," where you feel like you're awake and trying to move but can't. Alien abductions and ghost sightings generally fall into this category. A friend of mine in college once experienced a very vivid image of an Oz-style witch on a broomstick hovering outside his dorm room window!
