The Seven Myths of Medicine

This myth is so commonly believed that many people are prepared to lug around heavy bottles of water with them all day. The advice is interpreted to mean you should drink at least 8 glasses of water per day in addition to your normal eating and drinking.

But the fact is, there is no evidence to support the advice to drink eight glasses of water a day. Studies show that you get adequate fluid intake through typical daily intake of milk, juice, tea, coffee and soft drinks.

Some people think this claim was originally made by Albert Einstein, but there is no record that he ever said it. How would he know anyway? Einstein was a physicist, not a neurophysiologist.

In fact, studies of the brain -- including brain imaging, localization of function and metabolic studies -- reveal no dormant areas. Brain injury studies show that damage to almost any part of the brain has specific effects on capabilities whether mental, vegetative or behavioral.

This is untrue because growth of nails and hair requires sophisticated hormonal regulation not possible after death.

Johnny Carson popularized the notion with his oft-quoted joke: "For three days after death, hair and fingernails continue to grow, but phone calls taper off." Dehydration of the body post-mortem may cause the skin around fingernails to retract thereby creating the appearance of increased nail length.

Scientific studies have shown that shaving has no effect on hair growth.

Normal strands of hair taper gradually towards their ends, but shaved hairs lack this taper and consequently give the impression of coarseness or thickness. The part of a hair that is living lies beneath the skin and remains unaffected by shaving. Shaving does not affect rate or type of growth.

The great majority of studies in this area do not support this belief, but one review concluded that reading in dim light could result in impaired eye growth and refractive error. It is true that reading in poor light can lead to eye strain and discomfort from squinting. But, these effects do not persist.

Rates of myopia have increased over the past 100 years despite the fact that lighting conditions for reading were surely better using electric light than in previous centuries when people had to rely on candles and oil lamps.

This belief seems to derive from the fact that turkey contains the amino acid tryptophane, which is involved in sleep and mood control and can cause drowsiness. However, turkey contains no more tryptophane than chicken or beef and less than pork or cheese.

Many of us only eat turkey for Christmas dinner or Thanksgiving, when we accompany it with lots of stuffing, ham, vegetables and wine. Naturally you will feel drowsy after all of this.

There have been reports that mobile phones interfere with sensitive equipment such as cardiac monitors, and some hospitals ban the use of mobile phones in intensive care units. But the evidence shows that the extent of interference is quite low.

In a 2005 Mayo Clinic Study, 510 tests were performed with 16 medical devices and six mobile phones. The incidence of clinically important interference was 1.2 percent. Also, interference usually occurs only at distances less than 1 metre. Another 2007 study found no interference at all during 300 tests in 75 treatment rooms.