Changes to temperatures in children's bedrooms can affect their lung function for at least two weeks, according to a new study from the University of Otago.
Researchers from the Housing and Health Research Programme/He Kainga Oranga looked at more than a million temperature measurements in 405 homes.
They found that changes in children's bedroom temperatures were much more important than those in living room temperatures.
Researcher Nevil Pierse said the effects were greatest when children were exposed to temperatures of less than 12C, and a decrease in lung function was still detectable two weeks after exposure.
"Kiwi homes are much colder than those overseas. The World Health Organisation recommends children sleep in rooms no less than 20C, and the harm of changes below 12C is more than 10 times that of changes at 18C.