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: 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 8 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: 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: 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.
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: Mobile phones 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, mobile phones
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 mobile phones, the improved communication
means they make fewer mistakes.
