People with sleep apnoea are up to three times more likely to develop Alzheimer's disease and Australian researchers are determined to find out why.
More than one million Australians suffer from sleep apnoea, which occurs when the body's upper airways collapse during the night.
That causes intermittent pauses in breathing and in some cases hypoxia, where blood oxygen levels are too low and that's bad for part of the brain important for attention and learning.
University of Queensland scientists are about to test their theory that the intermittent nature of sleep apnoea - when breathing is disrupted, but only sometimes - could explain the higher Alzheimer's risk.
They also want to test if treating sleep apnoea with a respirator that's worn at night can slow brain degeneration and reduce subsequent dementia risk.
"When you go on a plane and you're high up, you don't have 100 per cent blood oxygen saturation but because that's constant your body can adapt to it," said UQ researcher Professor Elizabeth Coulson.
"But with sleep apnoea it's intermittent and we think those changes in blood oxygen levels means the body can't adapt and that's causing stress."
Prof Coulson and her team plan to recruit people aged 55 to 75 at the time they're diagnosed with Alzheimer's and follow them over time.