This is not surprising, because the skills required are different.  Daytime bladder control is under voluntary control, and can be taught.  (This is why it’s best to wait for potty training until your child is interested in staying dry.)  At night, though, the child is (hopefully) asleep, and has no voluntary bladder control.

Nighttime dryness is an unconscious act; it happens when the child’s brain becomes sufficiently mature.  Everyone achieves this state eventually, except in the rare event of a medical problem.  We label bedwetting as a problem only when it becomes a social issue, usually after age 6 or so when many children start to receive invitations for sleepovers at friends’ homes.  The medical term for this is “primary eneuresis,” indicating that the eneuresis or bedwetting does not have another medical cause.

Bedwetting often runs in the family.  Many children with prolonged bedwetting will have relatives who have also suffered with it (though some family members may be reluctant to discuss it).  These children generally are dry during the day, but they wet the bed several times per month, in some cases nightly, throughout childhood until they grow out of their bedwetting.  Limiting fluids in the hours before bedtime, and planned night awakenings for bathroom trips, can help.  Electronic beeper-style alarms, available for under $100, can teach kids to wake themselves over time.  If these measures are ineffective, there are safe and effective prescriptions available.

If a child begins bedwetting repeatedly after a dry period of months or years, it may be a sign of a different medical disorder requiring treatment.  This is called “secondary eneuresis,” and is less common than the inherited primary eneuresis.  A urine infection would be the most frequent culprit.

–  David Epstein, MD