Alien Abduction

Maybe they're just nuts, but not mentally ill. Kinda like Timothy Robbins:

[T]here is a striking similarity in alien abduction claims: such as big eyes, strange skin color of aliens, being "probed" by the aliens and telepathic communication.
Scientists argue that the reason for the accounts' similarity is that they are replicas of the alien depictions in the media. The aliens in most personal encounters are much like those we see in movies, television programs, and comic books.
But reactions are also similar. There is often a period of amnesia following the alleged encounter. Then the "witness" will usually undergo a session of hypnosis, counseling or psychotherapy to recollect the details of their extraterrestrial event. Some even endure psychological tests, which rarely confirm that abductees are mentally ill.
Richard McNally, Ph.D., psychological researcher at Harvard University told Psychology Today, "These people are almost never psychotic. They're not lying."
In fact, researchers have found that the abductees believe in their experiences to the point that they exhibit the same stress symptoms other victims of traumatic events display.
McNally recorded individuals that claimed to have been abducted as they related their experiences to him. When the tapes were played back, the abductees showed the same physical responses that survivors of war would show.
"The heart-rate responses and sweating responses were at least as great in the alien abductees when they heard their memories of being taken and molested by space aliens and subjected to experiments as those of people with genuine traumatic events," McNally told BBC News.
Still, others maintain their belief that these experiences are nothing more than overactive imaginations.
In the late 1980's, sociologist Robert Bartholomew and colleague Keith Basterfield studied 154 UFO contactees, concluding that 132 of these individuals displayed "fantasy prone characteristics." These whimsical dreamers had imaginary playmates as children and had more than one form of paranormal experience during their lifetime.

Link.