Myth: Shaved hair grows back faster, coarser and darker
Fact: A 1928 clinical trial compared hair growth in shaved
patches to growth in non-shaved patches. The hair which replaced the shaved
hair was no darker or thicker, and did not grow in faster. More
recent studies have confirmed that one.
Here's the deal: When hair first comes in after being
shaved, it grows with a blunt edge on top, Carroll and Vreeman explain. Over
time, the blunt edge gets worn so it may seem thicker than it actually is. Hair
that's just emerging can be darker too, because it hasn't been bleached by the
sun.
Myth: You should drink at least eight glasses of water a
day
Fact: "There is no medical evidence to suggest that
you need that much water," said Dr. Rachel Vreeman, a pediatrics research
fellow at the university and co-author of the journal article.
Vreeman thinks this myth can be traced back to a 1945
recommendation from the Nutrition Council that a person consume the equivalent
of eight glasses (64 ounces) of fluid a day. Over the years, "fluid"
turned to water. But fruits and vegetables, plus coffee and other liquids,
count.
Myth: Fingernails and hair grow after death
Fact: Most physicians queried on this one initially thought
it was true. Upon further reflection, they realized it's impossible. Here's
what happens:
"As the body’s skin is drying out, soft tissue,
especially skin, is retracting," Vreeman said. "The nails appear much
more prominent as the skin dries out. The same is true, but less obvious, with
hair. As the skin is shrinking back, the hair looks more prominent or sticks up
a bit."
Myth: We use only 10 percent of our brains
Fact: Physicians and comedians alike, including Jerry
Seinfeld, love to cite this one. It's sometimes erroneously credited to Albert
Einstein. But MRI scans, PET scans and other imaging studies show no dormant
areas of the brain, and even viewing individual neurons or cells reveals no
inactive areas, the new paper points out. Metabolic studies of how brain cells
process chemicals show no nonfunctioning areas.
The myth probably originated with self-improvement
hucksters in the early 1900s who wanted to convince people that they had yet
not reached their full potential, Carroll figures. It also doesn't jibe with
the fact that our other organs run at full tilt.
Myth: Reading in dim light ruins your eyesight
Fact: The researchers found no evidence that reading in dim
light causes permanent eye damage. It can cause eye strain and temporarily
decreased acuity, which subsides after rest.
Myth: Eating turkey makes you drowsy (tired and almost asleep)
Fact: Even Carroll and Vreeman believed this one until
they researched it. The thing is, a chemical in turkey called tryptophan is
known to cause drowsiness. But turkey doesn't contain any more of it than does
chicken or beef.
This myth is fueled by the fact that turkey is often
eaten with a colossal holiday meal, often accompanied by alcohol — both things
that will make you sleepy.
Myth: Cellphones are dangerous in hospitals
Fact: There are no known cases of death related to this
one. Cases of less-serious interference with hospital devices seem to be
largely anecdotal, the researchers found. In one real study, cellphones were
found to interfere with 4 percent of devices, but only when the phone was
within 3 feet of the device.
A more recent study, this year, found no interference
in 300 tests in 75 treatment rooms. To the contrary, when doctors use
cellphones, the improved communication means they make fewer mistakes.
"Whenever we talk about this work, doctors at
first express disbelief that these things are not true," said Vreeman
said. "But after we carefully lay out medical evidence, they are very
willing to accept that these beliefs are actually false."
