Bed-wetting (sometimes called enuresis), is unintentional urination during the night. Most children wet the bed occasionally, and definitions of the age and frequency at which bed-wetting becomes a medical problem vary. Many researchers consider bed-wetting normal until age 6. For a diagnosis of enuresis, wetting must occur twice a week for at least three months with no underlying physiological cause.

Enuresis is divided into two classes. A child with primary enuresis has never established bladder control. A child with secondary enuresis begins to wet after a prolonged dry period. Some children have bladder control problems during both day and night.

The causes of bed-wetting are not entirely known, but it tends to run in families. Most children with primary enuresis have a close relative who also had the disorder. Sometimes bed-wetting can be caused by a serious medical problem such as diabetes, sickle-cell anemia, or epilepsy. Snoring and episodes...