Medical Myths

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: 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: 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."