When Bill started to notice changes in his thinking, he never imagined that they could be signs of young onset Alzheimer's disease.
"I knew something was wrong, but I'd never considered it would ever be dementia," Bill says.
“I was a physics and chemistry teacher and had always relied on memory in the classroom. I started forgetting the names of students I'd taught for years. And as a deputy principal, I sort of prided myself on making good decisions and I suddenly started to struggle and tasks would take longer,” he says. “Then at the age of 59, I was diagnosed with young onset Alzheimer's disease.”
Earlier, another diagnosis had raised questions for Bill. He was found to have mild sleep apnoea, prompting him to wonder in retrospect whether there could be a connection between sleep and the disease he was living with.
As scientists uncover more about the role of sleep in brain health, his experience has become part of a broader conversation about how dementia might be identified, prevented and managed.
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Dementia is the leading cause of death in Australia, with almost 500,000 Australians are currently living with dementia. With that number expected to grow substantially in the coming decades, researchers are focusing on factors that may help to reduce risk.
Around 45 percent of dementia risk is linked to potentially modifiable factors – and alongside hearing loss, physical activity and cardiovascular health, sleep is now emerging as an important area of investigation.
Professor Sharon Naismith AM, a clinical neuropsychologist at the University of Sydney's Brain and Mind Centre and the Leonard P. Ullmann Chair in Psychology at the Charles Perkins Centre, is exploring the connection between sleep and dementia, and whether better detection and treatment of sleep disturbances could help to slow cognitive decline and improve the quality of life for people living with the condition.
Professor Sharon Naismith AM, clinical neuropsychologist at the University of Sydney's Brain and Mind Centre , Photo credit: Stefanie Zingsheim
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LinkSleep is about more than just rest. During the night, the brain consolidates memories and strengthens neural pathways.
“A really important component of sleep is that while we're sleeping, we actually lay down memories – we call it sleep-dependent memories,” Sharon says.
“The other thing we know about good quality sleep is that it's really important for the clearance of the toxins from our brains, so flushing out amyloid and tau proteins, which are involved in Alzheimer's disease.”
Sharon and her team are investigating whether conditions such as sleep apnoea and insomnia, or even sleep quality and duration may contribute to the disease’s progression, act as an early warning sign of cognitive decline, or both.
"There's a lot of research that suggests sleep is linked to dementia or that there's a bi-directional relationship," Sharon says. "With effective detection and treatment of sleep disturbances, we can potentially slow neurodegeneration and improve quality of life.
"We can also start to tackle these issues from midlife. We know the pathology associated with dementia begins to build up many years before symptoms appear, so we need to shift the dial towards prevention rather than waiting until it's too late," Sharon says.
Bill Yeates knows the importance of good sleep quality since living with his diagnosis, Photo credit: Stefanie Zingsheim
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LinkThere's a lot of research that suggests sleep is linked to dementia or that there's a bi-directional relationship.
Clinical Neuropsychologist
Understanding what happens during sleep is challenging. Traditionally, sleep research has relied on laboratory studies where participants stay overnight, connected to specialised monitoring equipment.
While these studies provide valuable information, they can also be expensive and may not fully reflect how people sleep in their own environment.
To overcome these challenges, Sharon and her team are developing approaches that allow sleep to be monitored over longer periods, at home.
“We're actually looking at ways that we can put wearable devices on people they can take home," Sharon says.
The devices include a headset that monitors brain activity and an oximeter worn on the finger that measures blood oxygen levels, helping researchers track sleep patterns over time.
In addition to wearable technology, researchers have developed an app designed to measure memory consolidation and track how effectively memories are retained from one day to the next.
By bringing together data from sleep monitoring technologies, wearable devices and cognitive tests, Sharon and her team are working to build a more complete picture of the relationship between sleep, memory and brain health.
The research also brings together expertise from across the University, including neuropsychology, sleep science, neurology, geriatrics, engineering and brain imaging to better understand how sleep affects the ageing brain.
"Putting all these things together, and coupling different technologies, helps us work out not only people's sleep, but also the brain processes that occur while they're sleeping," Sharon says.
Sharon Naismith with a patient at the Brain and Mind Centre, Image credit: Fiona Wolf
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LinkFor Bill, the research has helped explain a connection that was not obvious when he was first diagnosed.
"Making sure that I have quality sleep is such an important part of my journey with dementia,” Bill says. “We need to make sure my brain is clearing all that waste, all the toxins, as much as possible.”
Bill now serves on the project's sleep advisory panel.
"Being able to help researchers understand what's important to people living with dementia, and to give them my perspective on sleep, is something I really value."
While questions remain about the relationship between sleep and dementia, researchers believe the hours spent asleep may hold vital clues to how the brain ages. As Sharon and her team uncover more about what happens during the night, they hope to be able to identify cognitive decline earlier, improve treatment and help people to maintain brain health for longer.