Nocturnal enuresis (nighttime bedwetting) is common and can occur for many reasons, the most common being normal bladder maturation. The process of bladder control development is—the child first becomes aware of bladder filling, then develops the ability to urinate in the toilet. These skills usually are achieved during the day by approximately four years of age. Nighttime bladder control is achieved months to years after daytime control, but is not expected until five to seven years old.
There are many reasons that nighttime bladder control takes longer than daytime control: maturational delay (their bladder and brain need time to connect), genetic factors (bedwetting is common in family history) and small bladder capacity. Some parents of bedwetters may report that their child is a “deep sleeper.” However, this may be a bias of observation since caregivers rarely attempt to wake children without bedwetting.
Other things to consider include constipation and pelvic floor dysfunction. A child who has constipation may withhold urine and leak during sleep, while a child with dysfunction of the pelvic floor may have accidents during the day with laughing, sneezing and play, as well as nighttime wetting. There are many other reasons for bedwetting, such as neurological conditions, endocrine conditions, sleep apnea, urological conditions or infection.