In general, childhood bedwetting does not have an underlying cause and is not the child's fault. Reprimanding or embarrassing the child will only aggravate the problem further. Bedwetting may run in families and is twice as common among boys than among girls.

Causes

Some of the causes of bedwetting include:

Failure to wake up and use the toilet

Normally, when the bladder is full, a signal is sent to the brain that causes a person to wake up and go to the toilet. However, children under five years of age may sleep so deeply that they fail to wake up. This is due to underdevelopment of the nerves that carry signals along the spine from the brain to the bladder. Furthermore, even when children do wake up they may be too afraid of the dark to get up and go to the toilet.

Excessive fluid intake before bedtime

Compared with adults, children have a smaller bladder with less filling capacity and they are therefore more likely to wet the bed if they have had too much fluid during the evening or before bedtime.

Caffeine intake before bedtime

Drinking caffeine-containing drinks before bedtime can lead to increased bedwetting as caffeine is a diuretic and therefore increases urine output. Caffeine is found in drinks such as tea, coffee, Coca-Cola and hot chocolate, all of which need to be avoided if bedwetting is to be prevented.

Vasopressin deficiency

Excess urine production may be caused by a deficiency of vasopressin, a hormone that regulates urine production.

Overactive bladder syndrome

Some children may suffer from overactive bladder syndrome, a condition which causes the bladder muscles to contract more frequently, leading to excessive voiding of the bladder.

Medical conditions

Medical conditions that may cause bedwetting include type 1 diabetes, severe constipation, urinary tract infection, bladder stones, or abnormalities of the urinary tract or the nerves that connect the bladder to the spine.

Emotional experiences

Changes in emotion triggered by, for example, going to a new school, the introduction of a new sibling, moving house or parental discord may all lead to the incidence of bedwetting in a child who does not normally wet the bed. This condition is called secondary nocturnal enuresis. Children with clinical depression, attention-deficit hyperactivity disorder or behavioral problems may also develop a problem with bedwetting.