From Newsweek's top ten health myths, two of my least-favorite:
Reading in dim light ruins your eyesight. While
this is one myth that parents around the world have loved for
generations, it has very little scientific backing. Reading in the dark
can cause a temporary strain on the eyes, but it rapidly goes away once
you return to bright light. The practice has been blamed for increasing
rates of myopia (nearsightedness), but Carroll says those claims don't
align with the evidence—we're living in the best-lit conditions the
world has ever seen. "Seventy years ago we were reading by candlelight
and weren't going blind," says Carroll. "There's no evidence for this
whatsoever."
You should drink at least eight glasses of water a day.
The source for this myth may be a 1945 article from the National
Research Council that claims that a "suitable allowance" of water for
adults is 2.5 liters a day, although the last sentence of the article
notes that much of that water is already contained in the food we eat.
Existing studies suggest that that often-omitted fact is key to
understanding water intake. We get enough fluids from our typical daily
consumption of juice, milk and even caffeinated drinks. And drinking
too much water can cause water intoxication, a severe electrolyte
imbalance in which cells swell with excess fluid, and even death.
And, as an extra bonus, this one:
We use only 10 percent of our brains. The notion that
our brains are not running at full speed simply doesn't hold up.
"Numerous types of brain imaging studies show that no area of the brain
is completely silent or inactive. Detailed probing of the brain has
failed to identify the 'nonfunctioning' 90 percent," Carroll and Rachel
Vreeman, an assistant professor of pediatrics at the Indiana University
School of Medicine, write in the British Medical Journal study. Carroll
says the notion may go as far back as the snake-oil salesmen of the
early 20th century, who used the myth to sell a tonic that would
increase brainpower.
