Overview

As unpleasant as bed-wetting is for your child (and you), it's a natural part of childhood development. Twenty percent of 5-year-olds and 10 percent of 6-year-olds wet the bed, according to the American Academy of Pediatrics. And it's twice as common in boys as it is in girls. Here's what causes some kids to wet their beds, and how you can help your child stay dry through the night.

Why do kids wet their beds?

Bed-wetting, called "enuresis," is rarely an emotional or psychological problem. It doesn't mean your child is too lazy to get up and go to the bathroom or that she's stubborn or immature. Researchers have found that genes play a role. If both parents wet their beds after the age of 6, their child has about a 75 percent chance of doing the same; if only one parent wet the bed, the child has a 44 percent chance. The actual causes of bed-wetting are physical, which means your child has no control over them:

• She has a developmental lag. There are late walkers, late talkers  -- and late dry-nighters. And all eventually catch up.
• She may sometimes sleep so deeply that she fails to wake up when she needs to use the bathroom.
• She may have a small bladder that's more easily overfilled.

Nap time vs. nighttime

"Nighttime control can lag behind daytime control by a few months to a few years," says David Joseph, M.D., chief of pediatric urology at Children's Hospital in Birmingham, Alabama. A preschooler's bladder may still be too small to contain a night's worth of urine. Plus, it takes time to learn to recognize that almost-full feeling  -- and either wake up or instinctively hold it  -- especially if your child's a heavy sleeper. Nighttime dryness will happen naturally as your child learns to key in to his body's signals, and there are ways to (gently) help him along.