Australian researchers believe they may have found a possible mechanism to explain the association between poor sleep and Alzheimer's disease.

A person's genetics may influence the impact poor sleep has on their risk of Alzheimer's disease, an Australian study has found.

Researchers at Edith Cowan University (ECU) found individuals with particular genetic variations in Aquaporin-4 (AQP4) proteins reported poorer sleep and also presented with a build-up of beta-amyloid in the brain, key to Alzheimer's disease.

The study findings, published in journal Translational Psychiatry, adds to a growing bodying of evidence that suggests poor sleep is not just a symptom of Alzheimer's but a possible risk factor for the common form of dementia, says lead author Professor Simon Laws, head of the Collaborative Genomics group in ECU's School of Medical and Health Science.

"The initial thought was that poor sleep was a result of Alzheimer's disease but now we know that this is what we call a bi-directional relationship; that sleep may impact on the risk of Alzheimer's disease and then as one develops Alzheimer's disease it impacts upon sleep patterns, a bit like a vicious circle in a kind of a way," said Professor Laws.

"For the first time, we've found that people with genetic variants in AQP4 who also have problems getting to sleep and sleep for shorter periods have high levels of beta-amyloid in the brain," said Professor Laws.

Researchers analysed data from a large cohort study called the Australian Imaging Biomarkers and Lifestyle Study of Ageing (AIBL).

They then looked at a protein in the brain called Aquaporin-4 (AQP4), integral to what is known as the glymphatic system - a system the brain uses to 'flush' out toxins such as amyloid beta as people sleep.

The study found individuals carrying the AQP4 variants who only slept for six hours had high levels of amyloid in their brain but those who slept for eight or more reported low levels of the protein.

While more research is needed, the findings warrant further studies and research that look as sleep interventions to prevent Alzheimer's disease.

"In some individuals, their glymphatic system may function perfectly well on six or eight hours sleep, but this study suggests that individuals with a genetic variation might need more sleep," said Professor Laws.