We only use 10 per cent of our brains
Although you might think your batty uncle might be the perfect example, in fact scans show that all of the brain is active and playing a part in our thinking. Even small amounts of damage to the brain will cause mental impairment.
Sweets and other sugary treats make children hyperactive
Repeated studies have shown that children's behaviour is not affected by the amount of sugar they've eaten - although parents rate their children as being more hyperactive if they think they have given them a sugary drink, even if it is, in fact, just water!
Breast feeding causes saggy breasts
Good news mothers - this is false. A study by American plastic surgeons found that breastfeeding had no effect on the shape of women's breasts. However being overweight or a smoker were linked to saggier breast appearance, as were the number of pregnancies, size of breast before pregnancy and the age of the woman.
We should drink 8 glasses of water a day to avoid dehydration
There is no scientific evidence to support this widely believed and often followed myth. Tea, coffee, fruit juice - even the food we eat - all provide us with fluid. In fact excessive intake of fluid can damage the body and can even be fatal.
Spinach is high in iron
There must have been something else in Popeye's diet, because spinach is not all that rich in iron. Apparently, when it was first measured the decimal point was written in the wrong place, overstating the iron content of spinach by a factor of 10. Spinach contains about 1mg of iron per 100g, whereas dried figs have 4.25mg, roast beef 2.5mg and courgettes 2.4mg.
Warm milk helps you get to sleep at night
Milk contains the enzyme tryptophan which has been linked to the initial stages of sleep - but the amount in a glass of milk probably isn't enough to make us drowsy. But the psychological effect of warm milk at bedtime may be strong enough to put us in the mood for sleep!
Sick people should rest in bed
An analysis of 39 studies on the use of bed rest in treatment found that for many ailments staying in bed had no beneficial effect. In some cases it was actually harmful. Sorry, but going back to work is sometimes the best treatment!
You should wear a hat because we lose most of our body heat through our heads
Our heads don't give off any more heat than any other part of our body. If you are fully clothed then of course most of the heat will leave through your head because it is uncovered, but the same would be true for any other similarly sized body part.
Too much stress can give you ulcers
Actually, over 90 per cent of ulcers are caused by a bacterium, Helicobacter pylori.
If you are stung by a jellyfish you should pee on the sting
Before you start approaching people on the beach asking them to do the deed, you should know this is not true. There is nothing in urine that can counteract the effects of a jellyfish sting - in fact some stings will be further activated by it. But washing out the sting with warm water may alleviate the pain and prevent further skin damage, so this may be the source of the myth.