Primary nocturnal enuresis occurs when a child has gained bladder control during the day, but not at night.

The child must have experienced nighttime bedwetting consistently for at least six months before the situation is considered to be PNE.

(In contrast, secondary nocturnal enuresis occurs when the person has had daytime and nighttime bladder control for at least six months before experiencing consistent bedwetting during sleeping hours.)

Primary nocturnal enuresis can be caused by any number of things.

Among the most common causes is heredity.

Children who have a parent or other close relative who also experienced PNE are more likely to develop primary nocturnal enuresis.

Another common cause for consistent bedwetting is that the child sleeps so deeply that he or she doesn't wake up when the bladder sends a "full" signal to the brain.

Other frequent causes of PNE include a slow-developing central nervous system, a small bladder, urinary tract infection, urethral abnormalities, and attention deficit disorder.

A pediatrician can usually help pinpoint the cause of primary nocturnal enuresis and provide a solution to the bedwetting problem.