To help a 7-year-old overcome bedwetting, Dr. Howard Bennett reaches for red water balloons and a superhero named Bladderman. Bedwetting (search) is a problem for more than 5 million U.S. children age 6 or older.

Alarms and medicines are available, but understanding how their bodies work for many kids is key to staying dry — instruction that's a challenge to work into the typical rushed visit to the pediatrician.

Enter Bladderman, Bennett's creation and hero of the first book published by the American Academy of Pediatrics that's aimed directly at children, not just their parents.

The goal: To demystify bedwetting so that children understand accidents aren't their fault — it's not a matter of willpower but of biology — and to outline research-backed steps they can take to help stay dry.

Bedwetting "is common. You can ask for help," says Bennett, author of "Waking Up Dry" and a Washington pediatrician who specializes in treating what doctors call nocturnal enuresis.

Bedwetting is hard on youngsters' self-esteem. They may decline sleepovers or dread camp, or devise elaborate schemes, such as doing their own laundry, to hide the problem. Bennett even had a 9-year-old patient whose younger brother discovered his bedwetting and used it as blackmail.

Children usually get nighttime bladder control between ages 3 and 5. The brain and bladder must learn to work together: First, the bladder signals the brain that it's filling. The brain then either signals back for the bladder to relax and hold more urine overnight, or signals the child to awaken.

Occasionally, medical problems such as diabetes or anatomical abnormalities, cause bedwetting. But 85 percent of the time, it happens simply because the brain-bladder maturation isn't finished. Three main reasons:

—While people's bladders are all about the same size, some sense that it's full sooner than it really is. Bennett calls this a "small functional bladder."

—Some kids don't produce enough of a hormone called vasopressin that signals the kidneys to make less urine at night.

—Some children are difficult to arouse at night, and sleep through the tickle sensations of a full bladder.

Boys are twice as likely as girls to experience delays in nighttime bladder control, and bedwetting tends to run in families; whatever age mom or dad became dry usually is the age their own children will.

The good news: Fifteen percent of bedwetters become dry each year without any intervention.

For children who don't want to wait it out, there are ways to help. Most common are alarms that buzz or vibrate when they sense wetness. Studies show the alarms, which cost from $60 to $200, can help train children to wake up.

"But the education is crucial," stresses Dr. Patrick McKenna, chairman of urology at Southern Illinois University School of Medicine, citing studies that show good training in how the bladder works and how to control it can meet or exceed the devices' effect.

It requires an hour of doctor-child training, hard to squeeze into a busy pediatrician's schedule, McKenna says.

So parents often are left seeking more information on their own, from such sources as the National Kidney Foundation — which has some kid-friendly advice on its Internet site — and the pediatrics' academy.

Humor, Bennett says, eases kids' anxiety so they can learn: He regularly gets splashed as he uses water balloons to show his patients how the bladder's door, the sphincter muscle, controls urination.

Among his recommendations:

—Exercise that muscle by squeezing it several times a day.

—Limit liquid near bedtime, but drink two extra glasses of water earlier in the day to exercise your bladder. "We think if you pay attention to your bladder in the daytime, you'll pay more attention at night," Bennett explains.

—Kids should chart on a calendar how often they wet. Once they're dry for 14 consecutive nights, bedwetting likely is over.

—Tell kids it takes practice to achieve bladder control, just like sports stars practice their jobs daily — and offer small weekly rewards for the effort whether they stay dry or not, advice that mothers of two of Bennett's patients called key to maintaining children's enthusiasm.

There are bedwetting medications, including a synthetic version of vasopressin to reduce urine production. But Bennett and other specialists stress they should be a last resort; they have side effects and their effect is almost always temporary.

When pediatrician-based programs fail, urology specialists typically are called — but even with many hard-to-treat cases, bladder training without medication can help, says McKenna, who developed computer games that help youngsters exercise their pelvic muscles.