Turkey makes you drowsy. Dim light ruins your eyes. Drink at last eight glasses of water a day. These are some of the medical myths that even doctors believe, reports the British Medical Journal.
Myth 1. People should drink at least eight glasses of water a day.
The source may be a 1945 article from the National Research Council, part of the National Academy of Sciences, which noted that a “suitable allowance” of water for adults is 2.5 liters a day, although the last sentence noted that much of it is already contained in the food we eat. “If the last, crucial sentence is ignored, the statement could be interpreted as instruction to drink eight glasses of water a day,” Dr. Vreeman and Dr. Carroll noted. “Existing studies suggest that adequate fluid intake is usually met through typical daily consumption of juice, milk and even caffeinated drinks.”
Myth 2. We use only 10 percent of our brains.
The belief that we use only 10 percent of our brains has persisted for nearly a century, the authors noted. Sometimes the claim is attributed to Albert Einstein, but no reference or statement has ever been recorded. The study authors found references to this myth as early as 1907 and noted that it’s often repeated by people advocating the power of self-improvement. “Numerous types of brain imaging studies show that no area of the brain is completely silent or inactive,” wrote the authors. “Detailed probing of the brain has failed to identify the ‘non-functioning’ 90 percent.”
Myth 3. Hair and fingernails continue to grow after death.
The claim has been repeated in movies and talk-show monologues, but it’s not true. The growth of hair and nails requires “a complex hormonal regulation” that stops after the body dies. The reason for the long-held belief may be that dehydration of the body after death, and subsequent shrinking of soft tissue, can create the illusion of growth of hair and nails.
Myth 4. Shaving hair causes it to grow back faster, darker or coarser.
This common belief is often repeated in the media and reinforced when coarse stubble appears on the body after shaving. A 1928 clinical trial showed that shaving had no effect on hair growth, a finding confirmed by more recent studies. When hair grows back after shaving, it seems coarse because it doesn’t have the fine taper of unshaved hair. It seems darker because it hasn’t been exposed to the sun like the previously unshaved hair.
Myth 5. Reading in dim light ruins your eyesight.
The idea that dim light ruins eyesight probably has its origins in eye strain, said the study authors. Bad lighting makes it hard to focus, makes you blink less and leads to dry eyes, particularly if you’re squinting. So reading in dim light is uncomfortable, but it doesn’t cause permanent damage.
Myth 6. Eating turkey makes people especially drowsy.
This myth stems from the fact that turkey contains tryptophan, an amino acid found in proteins and essential to the human body. Scientific studies show that sleep and mood are affected by tryptophan.
Myth 7. Cellphones create considerable electromagnetic interference in hospitals.
Anecdotal reports persist that cellphones create false alarms on monitors and malfunctions in infusion pumps. But the study authors found no evidence to support it.In contrast, a large survey of anesthesiologists found that use of cellphones by doctors was associated with a 22 percent reduction in medical error resulting from delays in communication.
Myth 1. People should drink at least eight glasses of water a day.
The source may be a 1945 article from the National Research Council, part of the National Academy of Sciences, which noted that a “suitable allowance” of water for adults is 2.5 liters a day, although the last sentence noted that much of it is already contained in the food we eat. “If the last, crucial sentence is ignored, the statement could be interpreted as instruction to drink eight glasses of water a day,” Dr. Vreeman and Dr. Carroll noted. “Existing studies suggest that adequate fluid intake is usually met through typical daily consumption of juice, milk and even caffeinated drinks.”
Myth 2. We use only 10 percent of our brains.
The belief that we use only 10 percent of our brains has persisted for nearly a century, the authors noted. Sometimes the claim is attributed to Albert Einstein, but no reference or statement has ever been recorded. The study authors found references to this myth as early as 1907 and noted that it’s often repeated by people advocating the power of self-improvement. “Numerous types of brain imaging studies show that no area of the brain is completely silent or inactive,” wrote the authors. “Detailed probing of the brain has failed to identify the ‘non-functioning’ 90 percent.”
Myth 3. Hair and fingernails continue to grow after death.
The claim has been repeated in movies and talk-show monologues, but it’s not true. The growth of hair and nails requires “a complex hormonal regulation” that stops after the body dies. The reason for the long-held belief may be that dehydration of the body after death, and subsequent shrinking of soft tissue, can create the illusion of growth of hair and nails.
Myth 4. Shaving hair causes it to grow back faster, darker or coarser.
This common belief is often repeated in the media and reinforced when coarse stubble appears on the body after shaving. A 1928 clinical trial showed that shaving had no effect on hair growth, a finding confirmed by more recent studies. When hair grows back after shaving, it seems coarse because it doesn’t have the fine taper of unshaved hair. It seems darker because it hasn’t been exposed to the sun like the previously unshaved hair.
Myth 5. Reading in dim light ruins your eyesight.
The idea that dim light ruins eyesight probably has its origins in eye strain, said the study authors. Bad lighting makes it hard to focus, makes you blink less and leads to dry eyes, particularly if you’re squinting. So reading in dim light is uncomfortable, but it doesn’t cause permanent damage.
Myth 6. Eating turkey makes people especially drowsy.
This myth stems from the fact that turkey contains tryptophan, an amino acid found in proteins and essential to the human body. Scientific studies show that sleep and mood are affected by tryptophan.
Myth 7. Cellphones create considerable electromagnetic interference in hospitals.
Anecdotal reports persist that cellphones create false alarms on monitors and malfunctions in infusion pumps. But the study authors found no evidence to support it.In contrast, a large survey of anesthesiologists found that use of cellphones by doctors was associated with a 22 percent reduction in medical error resulting from delays in communication.
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