Abducted by Aliens: Believers Tell Their Stories

Stace Tussel, a single working mother and cum laude college graduate, has been reluctant to talk about her close encounters with extraterrestrials.

"I'm not necessarily fearful," she said. "I'm a bit nervous about how people may react. I do believe that I have experienced contact with non-human intelligence."

Tussel said she has videos and scars to prove it.

"I've had multiple witness sightings or experiences, but also marks that would show up on my body -- scars like the one on my finger," Tussel said. "I did wake up one time with three red diagonal lines. I've woken up with the handprints and fingerprints that I couldn't have made myself and nobody else could have made myself."

When asked if she's simply a more vivid dreamer than other people, Tussel said, "I don't know if dreaming would cause a stigmata-type effect where you're getting bodily scars or marks."

Tussel, an education consultant, blogs in her spare time about UFOs and crop circles. While many have been proven to be man-made hoaxes, she believes some crop circles could be the result of an alien spacecraft or extraterrestrial communication.

She doesn't care for the phrase "alien abduction," opting instead to call herself an "experiencer."

"I don't believe I was taken against my will," she said. "I believe that all my life, I've been prepared to share information, to experience information and contact with non-human intelligence."

Psychologists Say Media Images Re-Enacted in Dreams

But she prefers to leave the details of her experiences to the imagination.

Courtesy Terrell Copeland

27-year-old Terrell Copeland, who says he has had encounters with aliens, said he was known for being a quirky kid.

"I don't want to go into too much detail on certain kinds of beings that I saw because of the graphic nature of some of the things that I saw and experienced," she said.

While Tussel and others are thoroughly convinced, psychologists say the media-generated images of alien kidnappings can become easily engrained in our subconscious and then vividly re-enacted in our dreams.

"What tends to be similar is they come in the night, they take you some place, you're in a spaceship," Harvard University psychology researcher Susan Clancy said. "The aliens tend to look the same, which is that sort of greenish, triangular head, big eyes and they perform medical or sexual experiments on you."

Clancy and Richard McNally, who conduct psychological research examining false memories, believe a common disorder called sleep paralysis can explain why so many self-proclaimed "abductees" are absolutely convinced what they've experienced is real.

"A lot of people who had it think they're going crazy or they think that there are aliens or they think that there are ghosts out there," Clancy said. "And they're kind of freaked out."

Experts say sleep paralysis, the feeling of being awake, but unable to move during sleep, is quite common. Sufferers say they feel as if they're totally paralyzed -- a symptom that parallels what abductees like Copeland describe during their experiences with alleged extraterrestrial life.

"I couldn't move," Copeland said. "I was in complete paralysis, the only thing I could move were my eyes."

Clancy, herself, suffered from sleep paralysis and admitted that the feeling was so powerful that, for a moment, she was also convinced that her visions were real.

"It was so powerful at the time," she said. "While I'm levitating in the air -- that's what it felt like -- and spinning like a rotisserie chicken. I had this feeling that something was a presence. And I was thinking, 'Oh, my God, it's real.' But then it was over and then I woke up."

But for the majority of believers, Clancy said, their visions are likely facets of their imagination.

The abductees or experiencers ABC News spoke to reject any scientific explanation, asserting their belief that what they've been through is real.

"I can't sit here and tell you that I'm 100 percent sure what I say happened, happened," Copeland said. "It could be sleep paralysis. But I highly doubt it.

"I can remember vividly where I was, what I was doing and I was not awake. I could feel I was actually there."