Enuresis (medical name for bedwetting).
Enuresis refers to a repeated inability to control urination. Enuresis has no clear etiology; it is hypothesized to be related to genetics, sleep arousal dysfunction, maturational delay, stress, poor toilet training, altered smooth-muscle physiology, and occasionally organic causes. Most children in orphanages with enuresis have underlying psychological disorders; like poor self-esteem, family stress, and social isolation.
This problem can be solved by consulting a doctor and the most important - by loving and caring parents.