CKisMom wanted advice on nighttime potty training for her 3 1/2 year old, who uses the bathroom by himself during the day but still needs a pull-up at night. He doesn't drink much before bed and uses the bathroom before lights out, but isn't staying dry.

Dr. Katherine Hopkins, a pediatrician with Box Hill Pediatrics in Abingdon, says it's actually common for kids to wet the bed until they're as old as 7. "If there is a family history of bedwetting, then a later age for night-time control is common," she wrote to me. "The first step in the pursuit of over-night dryness is to evaluate the child’s evening routine. Late dinners, after-school activities with a large drink bottle and bed-time snacks will contribute to the volume of fluid heading to the bladder overnight. Encourage plain water rather than sugary drinks or milk in the evening. Use a smaller glass." (But don't over-restrict water from a child who has reason to be thirsty from physical activity.) "Be sure your child empties his/her bladder just before going to sleep."

If those steps don't work, your child is likely just a heavy sleeper whose need to get to the bathroom isn't waking him up. When he's 7 to 9 years old, you can try intervening with an alarm that attaches to the child's underwear and sounds at the first sign of urine. Because the child may not hear that, Hopkins recommends a parent sleep in the room with the child at first.

"Once the alarm sounds, the parent jumps up, wakes the child (trying to stop the urine flow) gets the child to the bathroom, change the towel on the sheets (which was placed there at the beginning of the night to make clean-up quick) and all go back to sleep till the next alarm," she wrote. "This process usually takes a good 3 to 4 weeks, so you have to be patient and committed!" Eventually, the child should either get up to use the bathroom during the night on his own, or stay dry.

Hopkins recommends consulting your own pediatrician about which alarm is right for you, particularly if your child has other health issues. And if the alarm strategy fails, you might want to talk to the doctor about medication, especially if the child is avoiding camp or sleep-overs because of embarrassment.

By the way, she says daytime wetting or stooling accidents and constipation can be a sign of a more serious medical condition and need to be addressed by a pediatrician sooner rather than later.