Wake up and smell the turkey: Study exposes medical myths
Feeling sleepy? Don't blame the leftover turkey.
The holiday favorite's nap-inspiring powers have been greatly exaggerated, according to a new paper that debunks common health myths.
Authors say they were surprised by how little evidence they could find to support many common assumptions. But they note that doctors actually perpetuate many of these myths, even though they're untrue or unproven.
Before writing the paper, "even I thought that turkey makes you sleepy," says co-author Aaron Carroll, director of the Center for Health Policy and Professionalism Research at Riley Hospital and Indiana University School of Medicine.
Some medical myths can cause consternation at hospitals. Emergency departments, for example, have been known to reserve X-ray machines on Halloween in case a child swallows a razor blade hidden in candy, Carroll says. He says that children are actually in far greater danger of being struck by a car while trick-or-treating than of being harmed by strangers.
Carroll and co-author Rachel Vreeman selected seven myths for their paper in last week's British Medical Journal.
Turkey makes you fall asleep.
Although turkey contains tryptophan, an amino acid involved in sleep and mood control, beef and chicken contain just as much tryptophan. And a ham and cheese sandwich has even more, Vreeman says. Eating turkey with other foods, such as stuffing and sweet potatoes, probably dilutes tryptophan's effects, says Sue Moores of the American Dietetic Association, who was not involved in the paper. People may nod off on holiday afternoons because they've eaten a big meal capped off with alcohol, Moores says. An afternoon of eating shuttles blood to the stomach and away from the brain. Sitting around in a warm room also can make people drowsy.
You should drink at least eight glasses of water a day.
People do need about this much fluid a day, Vreeman says. But they can get much of it from foods, such as fruits and vegetables, or beverages such as coffee and tea.
We use only 10% of our brains.
Although Albert Einstein has been credited as the source of this claim, studies show that no area of the brain is completely inactive, according to the paper.
Hair and fingernails continue to grow after death.
Although it's captivatingly ghoulish, it's not true, Carroll says. Nails and hair may appear to lengthen only because the skin around them is shriveling up and pulling away.
Reading in dim light ruins your eyes.
While reading in the dark may cause temporary eye strain, there's no evidence that it causes permanent damage, the paper says. People are more likely to harm their eyes by failing to wear sunglasses outdoors, says Andrew Iwach, a doctor and spokesman for the American Academy of Ophthalmology who was not involved in the study.
Shaving your hair makes it grow back faster and coarser.
Hair is actually no thicker after it has been shaved. And its growth rate doesn't change, Vreeman says, noting that stubble's thick appearance is an optical illusion. Uncut hair appears lighter or finer only because it has been bleached by the sun or chemicals. And uncut hairs may taper more smoothly at the end than hair that has been bluntly cut by a razor.
Cellphones cause hospital equipment to misfire.
Although reports of malfunctioning machines in the early 1990s led many hospitals to ban cellphones, a 2007 study found no interference from cellphones in 300 tests, according to the article, which notes that improved technology has made phones safer. Using mobile phones can actually prevent errors, authors note, because doctors can communicate with one another more quickly. Vreeman and Carroll plan to fill an upcoming book with even more medical myths, including playground favorites about strangers poisoning Halloween candy — there has never been a documented case — and swallowed chewing gum accumulating in the stomach. Kids of America can rest easy, Vreeman says: Gum "just passes through."