Have you seen a ghost? There may be a medical reason

Spooky footsteps, faint figures, the feeling of being watched — these unsettling signs of a ghost are as familiar to us as goose bumps on the back of our arm or neck.

Are there physiological explanations for those things that go bump in the night?

Absolutely, said Joe Nickell, a senior research fellow for the Committee for Skeptical Inquiry, an organization that promotes scientific inquiry and critical investigation of paranormal and other extraordinary claims.
“I’ve investigated haunted houses, inns, theaters, graveyards, lighthouses, castles, old jails, and even office buildings,” said Nickell, who’s researched stories of ghosts, vampires, werewolves, sea monsters, psychic phenomenon and other unusual phenomenon for 40 years. “And I’ve never found a paranormal explanation.”

“Ghosts” are often the result of pranks, environmental phenomenon, or physiological conditions such as sleep paralysis and the hypnogogic and hypnopompic hallucinations that accompany it, Nickell said.

Waking dreams
Sleep paralysis occurs when there’s a disconnect between mind and body while people are going in or coming out of REM sleep, said Dr. Priyanka Yadav, a sleep specialist at the Somerset Medical Sleep for Life Center in Hillsborough, N.J.

“It can last from a few seconds to a minute or two and is often associated with hypnagogic hallucinations, things you might see when trying to fall asleep or hypnopompic hallucinations, things you see when you’re trying to wake up," said Yadav.

These “waking dreams” can involve serpents, spiders, intruders, and yes, even ghosts and are often associated with feelings of dread.

“Some people have visions where they feel something is trying to strangle or choke them or they have a sense of impending doom,” said Yadav. “They’ll often see someone coming into their room and they’re not able to move or talk or scream or do anything.”
The phenomenon, which has been suffered by humans for centuries, also explains both the demonic visitations people reported during the Middle Ages — as well as modern reports of alien abductions, said Nickell.

People who report hauntings will often experience them just as they go to bed or in the middle of the night.

“They’ll tell you they couldn’t move," said Nickell. "That’s enough to diagnose it right there. It’s extremely common and very, very often the simplest and best explanation for a ghost.”