Australian researchers have connected sudden infant death syndrome to low levels of a brain protein which regulates sleep arousal in a major breakthrough in understanding the disease.

Researchers at Sydney's Westmead Children's hospital have found evidence that babies who die from sudden infant death syndrome, sometimes known as 'cot death', have low levels of orexin, a brain protein which regulates sleep arousal.

Scientists found that low levels of the same protein were found in the brain of adults with obstructive sleep apnoea, a condition that causes pauses in breathing while asleep.