Enuresis is the involuntary discharge of urine. It may be nocturnal, diurnal - during the day - or both. It normally however refers to the involuntary discharge of urine during sleep at night; nocturnal enuresis.

Nocturnal enuresis (bedwetting) is common among school-aged children (1):

• more common in boys than girls
• around one in six 5-year-olds, and at least one in fifty 7-year-old boys and one in a hundred 7-year-old girls, have nocturnal enuresis (wetting the bed) more than once a week
• in some children, the problem can persist, with around 0.8% of girls and 1.6% of boys aged 15-16 years wetting at least once every 3 months

Daytime enuresis is less common and it has been estimated that it may occur in 2% of 5 year old children and this becomes less frequent with age.

Diurnal (daytime) enuresis is more common in girls than boys, and it is often accompanied by nocturnal enuresis.

Reference:

• (1) Drug and Therapeutics Bulletin (2004), 42 (5): 33-37.
• (2) CSM/MCA (1996), hyponatraemic convulsions in patients with enuresis treated with vasopressin, Current Problems in Pharmacovigilance, 33, 4.