It is the inability to maintain urinary control during sleep.
Primary enuresis refers to inability to maintain urinary control from infancy.
Secondary enuresis is a relapse after control has been achieved. Medical disorders like diabetes, urinary tract infection, sleep apnea or epilepsy can cause it. Psychiactric disorders can also be a cause. To be considered sleep enuresis, there has to be at least two episodes per month in children 3 to 6 years and at least one episode per month for older individuals. Sleepwalking can also occur during an episode.