'Breakthrough' in SIDS research could lead to screening test

Australian scientists may have found the first biological explanation for why some newborns die suddenly in their sleep.

Researchers at The Children's Hospital at Westmead said they have discovered that babies who die from Sudden Infant Death Syndrome (SIDS) have greatly decreased levels of a certain brain protein, known as Orexin, responsible for regulating sleep arousal.

It's hoped the "breakthrough" research will one day lead to babies being screened for this protein.

Such a test would not be available for at least another decade, however, and parents still need to follow the SIDS prevention guidelines, experts caution.

There are many well-known and evidence-based environmental risk factors related to SIDS, such as smoking, excessive bedding and stomach sleeping.

Dr Rita Machaalani, the sleep unit manager at Westmead, said they now have evidence that SIDS is caused by a biological defect in an area of the brain responsible for sleep regulation.

A cohort study of more than 27 SIDS cases and 19 controls found the level of Orexin was 20 per cent lower in the brains of those babies who had died from SIDS.

"That seems to indicate that these babies may have had some defect in the message that says this baby should arouse during their sleep time but it didn't get through to do so," Dr Machaalani said.

Dr Machaalani said her team was conducting research to find the mechanism responsible for this reduction in Orexin, which has previously been implicated in sleep disorders in adults.

Medical researcher, Associate Professor Alexandra Martiniuk from The George Institute for Global Health at the University of Sydney, said the potential to screen was huge.

But this protein could be just "one of many" causes of SIDS, Assoc. Prof. Martiniuk added.

"I have read a lot of coroner reports of children who have died of SIDS and there are these other risk factors. They do often state that they found the child lying face down or face embedded between mattress and something else."

Assoc. Prof. Martiniuk said SIDS could be the result of a combination of both biological and environmental factors, such low levels of Orexin and bad sleeping habits.

"It will remain to be seen whether you need a loading of risk factors to have a bad outcome of death.

"But certainly it's a huge breakthrough because in my knowledge of SIDS there hasn't been anything biological like that before, it has always been environmental risk," she said.