Causes

No one knows for sure what causes bed-wetting, but various factors may play a role:

• A small bladder. Your child's bladder may not be developed enough to hold urine produced during the night.
• Inability to recognize a full bladder. If the nerves that control the bladder are slow to mature, a full bladder may not wake your child — especially if your child is a deep sleeper.
• A hormone imbalance. During childhood, some kids don't produce enough anti-diuretic hormone (ADH) to slow nighttime urine production.
• Urinary tract infection. This infection can make it difficult for your child to control urination. Signs and symptoms may include bed-wetting, daytime accidents, frequent urination, red or pink urine, and pain during urination.
• Sleep apnea. Sometimes bed-wetting is a sign of obstructive sleep apnea, a condition in which the child's breathing is interrupted during sleep — often due to inflamed or enlarged tonsils or adenoids. Other signs and symptoms may include snoring and daytime drowsiness.
• Diabetes. For a child who's usually dry at night, bed-wetting may be the first sign of diabetes. Other signs and symptoms may include passing large amounts of urine at once, increased thirst, fatigue and weight loss in spite of a good appetite.
• Chronic constipation. The same muscles are used to control urine and stool elimination. When constipation is long term, these muscles can become dysfunctional and contribute to bed-wetting at night.
• A structural problem in the urinary tract or nervous system. Rarely, bed-wetting is related to a defect in the child's neurological system or urinary system.