Nighttime bed-wetting, called enuresis by doctors, affects about 40 percent of 3-year-olds, according to the American Academy of Pediatrics. By age 5, it is down to about 10 percent, according to the National Institutes of Health. By age 6 or 7, only 5 percent of children wet the bed at night, says Dr. Mouin Seikaly, medical director of the Kidney and Gynecology Center at Children's Medical Center of Dallas.

Causes for bed-wetting vary for different children. Some causes include a child having a small urinary bladder capacity or the inability of the child’s body to concentrate, or reduce urinary volume, at night. Genetics often play a role; the condition runs in families.

"Nighttime bed-wetting appears to result from a combination of physical and behavioral factors," Dr. Seikaly adds. "We also know that the problem becomes worse under stress."

Some children wet the bed every night — once or several times, while others wet the bed intermittently, explains Dr. Seikaly. Most children who wet the bed do so once a night. An impermeable mattress cover will make life easier.

But there is one thing Dr. Seikaly says parents should know about enuresis: The family should avoid scolding a child for bed-wetting. This will only make the problem worse.

"You will need to keep your child on a schedule, restrict fluids close to bedtime and awaken your child two to three hours after going to bed so she can go to the bathroom," says Dr. Seikaly.

Several treatment options are available. These need to be discussed with your child’s pediatrician because only she can recommend what is best for your child.

Your doctor may suggest trying medication, but most wait until a child is 6 years old and still having a problem.