The involuntary passing of URINE during sleep. It is a condition predominantly of childhood, and although it is usually genetically determined, it can be a symptom of anxiety, especially if there have been over-rigorous attempts at toilet-training or hostile or unloving behaviour by a parent. It can also be provoked by what adults might see as unimportant changes in a child's life – for example, moving house. In a small minority of cases it is due to some organic cause such as urinary tract infection.

The age at which a child achieves full control of bladder function varies considerably; sometimes it is during the second year, but much more commonly not until two or three years old. Some children do not achieve full control until their fifth year, so that paediatricians are reluctant to make a diagnosis before a child is aged six.

The approach to treating children over five years consists of reassuring the child that they are neither ‘dirty’ nor ‘bad’, together with firm but kindly and understanding training. In most cases the use of a ‘star chart’ and a buzzer alarm, which wakens the child should he or she start passing urine, is helpful. Where there are relationship or social problems, these need to be understood and dealt with. The few who have urinary infection or irritable bladders may respond to drug treatment.

Those who do not respond may be helped by DDAVP or desmopressin, an analogue of a pituitary hormone, which reduces the amount of urine produced overnight. It is licensed for use for three months at a time. Some people prefer to reserve it for occasions such as sleeping away from home. The antidepressant imipramine is licensed to treat enuresis in children.