By Diane Mapes

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

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

Absolutely, says 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, theatres, graveyards, lighthouses, castles, old jails, and even office buildings,” says 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.”

Instead, Nickell says “ghosts” are often the result of pranks, environmental phenomenon, or physiological conditions such as sleep paralysis and the hallucinations that accompany it.

By Bill Briggs

Let’s start by driving a stake into the heart of some olds myths. People who have a sun allergy are not restless creatures of the night. They are not undead – although they may feel that way after, say, watching a marathon of the sun-drenched bikinfest “The Hills.”

While sunbeams don’t turn their skin sparkly, one brief exposure to solar rays may send them screaming back to their dark places or, at least, to the doctor’s office.

Who are these people who dread the daylight? Chances are you know one. You may even be one.

By some estimates, 45 million Americans – most of them northerners – are so hypersensitive to ultraviolet light that the first splash of spring sun causes itchy, red rashes or patches of small, red bumps to flare on uncovered areas of their chests, backs, upper arms, bellies or shoulders. They have a common condition called polymorphic light eruption (PLE), found in about 10 to 15 percent of people in North America.

By Diane Mapes, contributing writer

Turns out Mom was right yet again. You can scare yourself to death, although not necessarily by watching Halloween horror movies.

Dr. Martin A. Samuels, who studies the sudden death phenomenon, says some people do have the potential to suddenly drop dead from fright.

“It’s a relatively uncommon thing, but it does happen,” says Samuels, chairman of the department of neurology at the Brigham and Women’s Hospital in Boston. “You can even find references to it in the Bible.”

Not to mention Edgar Allan Poe’s “The Pit and the Pendulum,” Sir Arthur Conan Doyle’s “The Hound of the Baskervilles” and even recent headlines (“Robber scared grandmother to death”.)

How can a person literally drop dead from fear?

By Diane Mapes

The phenomenon of hair turning white from fright (or shock or grief or stress) persists in literature, poetry and even a handful of medical journals.

But is there any truth to the rumor that we can actually scare our hair?

Yes and no, says dermatologist Dr. David Orentreich, associate director of the Orentreich Medical Group in New York and assistant clinical professor in the department of dermatology at Mount Sinai School of Medicine.

“It’s appealing on a literary or poetic level that a person’s experience could be so severe or terrifying that they age overnight,” he says. “But you can’t lose pigment in your hair. Once it leaves your scalp, it’s non-living, it’s dead."

But, Orentreich says, while fear can’t suddenly cause your hair to turn white, there is a medical condition that could make people think it has.

By Diane Mapes, contributing writer

We all get busy at times, so overwhelmed with work, family, friends and obligations that we neglect our bodies. But how is it possible to be so out of touch with your body that you don’t know you’re about to give birth?

Easy, say the people involved with “I Didn’t Know I Was Pregnant,” a 10-episode reality TV show that tells the story of 10 women who conceive and carry babies full term without realizing they’re pregnant.

“I think at first glance you think, how could a woman not know,” says Wendy Douglas, director of production for the TLC network. “Clearly she’s not paying attention or not smart or something. But that’s really not the case.”

By Brian Alexander, contributing writer

After South African runner Caster Semenya came out of nowhere to zip past a track of world-class athletes in the women’s world 800-meter race in Berlin last month, spectators starting speculating that the muscle-bound 18-year-old was no lady. Her low voice and broad shoulders raised eyebrows and suspicions.

Now, newspaper reports from Australia say testing has determined that the running star has both male and female sexual organs – in other words, that she’s a hermaphrodite, and likely didn’t even realize it.

The International Association of Athletics Federations, which ordered the testing, refused to confirm or deny the reports and said it won’t issue a final decision for a couple of months.

In the meantime, there is worry about how the 18-year-old from a poor village in South Africa will handle the scrutiny, and widespread curiosity about what “hermaphrodite” means, exactly.

by Diane Mapes, contributing writer

When Arkansas mom and reality TV star Michelle Duggar announced on the Today show Sept. 1 that she was pregnant with her 19th child, millions of Americans expressed joy and amazement.

But others – undoubtedly the queasiest of the bunch – were a bit uneasy. How could one woman – or rather, one uterus – bear so many children? Isn’t that, well, stretching things a bit?

Not necessarily, experts say.

“The uterus is a remarkably flexible organ,” says Dr. Florence P. Haseltine, ob/gyn and founder of the Society for Women’s Health Research in Alexandria, Va. “It can grow rather rapidly and it can recede rather rapidly. It’s able to reconstruct itself and reconfigure itself quickly.”

By JoNel Aleccia

At last, good news for anyone who ever despaired of fitting into skinny jeans: Thin thighs might actually kill you. Or at least put a strain on your heart.

That’s the word from Danish researchers who studied more than 2,800 middle-aged people for up to a dozen years, only to find that those with the slimmest thighs had the highest chance of heart disease and premature death.

“There was up to a double risk for the people with the smallest thighs,” said Dr. Berit L. Heitmann, a director of research at Copenhagen University Hospital in Denmark. “It’s quite substantial.”

People whose thighs measured less than 60 centimeters, or about 23.6 inches in circumference, were in trouble. And those with stick-thin gams (less than 18 inches around) were at the greatest risk, according to a new study in the online version of the British Medical Journal.

By that measure, supermodels everywhere would be in grave danger, while those who one fitness expert described as “normal-sized people,” would be in the pink.

“Typically a 23.6-inch thigh on a female would be a size 6 to 8,” said Greg Benson, president of the International Sports and Fitness Trainers Association.

By JoNel Aleccia

A disabling disease that can turn human hands into virtual claws may be eased or even cured by an injectable drug now under review by the federal Food and Drug Administration, a new study suggests.

The drug, called Xiaflex, could be an alternative to surgery for Dupuytren’s contracture, a benign but often crippling disorder in which collagen cords form in the hand, curling the fingers immovably into the palm, according to a report in today's New England Journal of Medicine.

Dupuytren’s is named for Baron Guillaume Dupuytren, the 19th-century French surgeon who described the disease now believed to affect some 13.5 million to 27 million people in the United States and Europe.

Ronald Reagan had the condition. Britain’s Margaret Thatcher has it, too. And J.M. Barrie, author of “Peter Pan,” may have used his own experience with Dupuytren’s as a model for the character of Captain Hook.

“It’s claw-like, if you will,” said Rod Van Sickle, 63, a retired Trabuco Canyon, Calif., firefighter who had to take a desk job after Dupuytren’s ravaged his hands. He had three surgeries on his right hand to correct the recurring condition before it shifted to his left. (A common pattern for the mysterious condition.)

By Diane Mapes

We do it when we’re sick, when we’re cleaning out our closets and, according to a recent YouTube chat with astronaut David Wolf, we do it in space. Even pandas do it.

Few really understand what’s happening when our noses explode in a sneeze. As we head into cold season and the dreaded return of swine flu, even the most innocent sneeze (Do you have a cat?!) can spread paranoia. Let go with a noisy honk and watch the uncomfortable reaction, or downright hostile stares, of nearby strangers. But are those powerful sneezes — called sternutations — proof that we’re carrying some kind of virus? Why do we sneeze anyway?