Approximately 750,000 children over the age of five in the UK wet themselves; by the age of 10 one child in 20 still wets the bed. Bedwetting, or nocturnal enuresis, is more common than many people think, yet it causes parents much anxiety.

The causes are varied and can range from poor diet to emotional trauma or simply habit. It also tends to run in families. More than 75 per cent of children who wet the bed have a parent who wet the bed after the age of five. Children with this problem may be slower to develop the complex system of co-ordination between the nerves and the muscles controlling the bladder. They also may not be producing enough of a hormone, vasopressin, which concentrates urine during the night.

For some reason, boys and firstborn children tend to wet the bed more often than girls or subsequent children.

There are two main ways to treat bedwetting. The first is an alarm system, of which there are two types. One is a bed alarm, which consists of a sensor mat placed under a child's mattress that is connected to a sound box placed by the bed. The other is a body alarm, a sensor that fits inside a child's underwear and connects to a small sound box.

Both work in the same way: when your child begins to wet the bed, the alarm sounds. The idea is that the child wakes up and goes to the toilet.

The second treatment is medication. Overnight we naturally produce more of the hormone vasopressin, which concentrates the urine. Children who wet the bed tend not to produce vasopressin at night (though this problem may correct itself with age). As a result, they produce a greater volume of urine. This can be treated with a synthetic preparation of vasopressin, squirted via a spray up the nose or by taking pills. It simulates the effects of the hormone and concentrates the urine. Other medication can work by raising the threshold of awareness of a full bladder.

The initial success rate for both treatments is about 70 per cent. However, about 30 per cent of children go back to bedwetting once treatment has been discontinued. The following charity can offer help:

Education and Resources for Improving Childhood Continence: http://www.eric.org.uk