Bedwetting could be linked to breathing problems, researchers have suggested.
Half a million children in the UK wet the bed
It could even be an explanation for incontinence in some adults, the Australian team says.
Past studies have shown that when children have adenoids or tonsils removed, their bedwetting stops.
But the researchers say a blocked airway could also cause problems.
UK experts say all children who are have night-time incontinence problems should be examined to see if it could be caused by breathing difficulties.
Around half a million children in the UK are affected by bedwetting.
Dr Derek Mahoney, an orthodontist at the Prince of Wales Hospital in Sydney, Australia, said eight out of 10 children referred to him for bed-wetting problems have a narrow palate.
If the roof of the mouth is particularly narrow, the tongue is pushed back and can partially block the airway during sleep.
Children can be given a device, similar to a brace, to widen the palate.
In a previous Swedish study, seven out of 10 children who had not responded to any other treatment saw improvements after using the brace.
Four stopped wetting the bed completely.
Another British study found bedwetting stopped in 10 out of 10 children given the brace.
Dr Mahoney is about to begin a larger study on 100 children.
He will monitor their sleep patterns and bedwetting episodes.
Although it is unclear how breathing problems and bedwetting are linked, researchers say there could be a number of explanations.
One is that breathing problems create a physical pressure in the abdomen that stimulates urination.
Another is that the breathing problems can lead to low blood oxygen concentrations, which can then affect the levels of hormones involved in urine production.
Dr Dudley Weider, of the Dartmouth-Hitchcock Medical Center in Hanover, New Hampshire, has followed over 300 children with bedwetting problems who had surgery for airway obstruction.
He said a quarter stopped wetting their beds virtually straight away.
Another 50% stopped within six months.
Penny Dobson, of the UK's Enuresis Research and Information Centre, which helps sufferers of night-time incontinence, told BBC News Online a link with breathing problems had been suggested by other researchers.
"This research indicates that these sorts of questions should be asked of all children who wet the bed.
"It could be the solution for some."
The latest research is published in New Scientist.