They have embarked on New Zealand's most comprehensive study into preschoolers who snore, a study they hope will eventually involve 90 snorers and 90 control children.
An estimated 8%-10% of children snored, Dr Galland said. The most common causes were obesity and enlarged adenoids or tonsils restricting the airways, although snoring could also be hereditary.
Her team has recorded some children snoring at 70 decibels - as loudly as a lawnmower or a household vacuum cleaner.
But disturbing the peace of a sleeping household was not the major concern, she said.
"People often think it is funny when children snore, or that snoring is harmless. But snoring and disturbed sleep can impact on children's behaviour, concentration and academic potential, and can lead to serious sleep problems in adulthood."
The two-year study, which began in July, aims to quantify differences in daytime learning and behaviour between children who snore and children who do not.
The team is still trying to fill places in the study. Letters have been sent to the parents of 1800 children born at Queen Mary Maternity Hospital between 2004 and 2006, but families who have moved to the greater Dunedin area were also invited to participate, Dr Galland said.
"We need lots of children. We need ones who snore, and we need the control children as well."
All children selected for the study wear the electronic pyjamas in their own beds for five nights. Their parents fill in a sleep and daytime diary and their early childhood teachers answer questions about learning ability and general behaviour. The exercise is repeated one year later.
PhD student Amelia Gill is leading the field studies, with assistance from Carmen Lobb, and it is their job to kit the children up for their bedtime experiences. Modified pyjama tops and a cloth bag containing a data recorder will be used to enable the researchers to hear the children breathing and snoring, to measure their oxygen levels, and to count the number of times they momentarily stop breathing and move around in bed.
Most children reacted well to the monitoring, Ms Lobb said.
"Some can be a bit unpredictable. On Monday, they won't have anything to do with the pyjamas and on Friday, they want them them back. But most of them have been amazing."
Other studies had shown most children grew out of snoring by the time they were about 9, Dr Galland said.
However, children of all ages who snored severely because of adenoid or tonsil problems might need their tonsils and adenoids removed to improve their sleep and their health.
She said she hoped the Dunedin study would help identify the critical point when snoring was severe enough to warrant a surgical intervention.
