Bedwetting is common for children, affecting more boys than girls. The condition occurs in 30% of children at the age of 4, 16% at the age of 6, and drops to 1-2% by the age of 18. Although children develop bladder control at different rates, most boys can control their bladder during the day and night by the age of 6, and most girls by the age of 5. When a child who is old enough to have bladder control urinates accidentally while sleeping, it's called nocturnal enuresis.
There are 2 main types of nocturnal enuresis: primary and secondary.The primary type is a condition where a child still wets the bed after age 5 or 6. It's often hereditary. The secondary type occurs when a child who had stopped bedwetting for at least 6 months starts again, often due to emotional stress or a medical condition.
Possible causes of primary nocturnal enuresis include the following:
- delay in maturation of bladder control
- genetics – children with parents who also wet the bed beyond age 5 are at an increased risk for bedwetting
- sleeping deeply – this may make children less aware of cues for the need to urinate
- constipation – this may not allow children to empty their bladder completely
- voiding patterns – children who suppress their urge to urinate or postpone voiding may not develop coordination with sphincter control and bladder control
Rare possible causes include the following:
- problems with antidiuretic hormone (ADH), a hormone that causes the body to retain water – Normally, ADH levels increase at night to decrease the amount of urine produced. However, children with enuresis do not have increased ADH levels at night, causing greater urine production, which can lead to wetting.
- minor nerve damage - this may decrease a child's ability to sense a full bladder
Although it is often said that emotional stress causes primary nocturnal enuresis, there is little scientific evidence to support this claim. However, bedwetting itself may lead to feelings of shame and lowered self-esteem.
Causes of secondary nocturnal enuresis include the following:
- emotional stress (e.g., birth of a sibling, significant loss, family discord)
- urinary tract infection
- diabetes mellitus (rarely)