Sleep and neurodegeneration: over a million health records

Research led by Cardiff University (UK Dementia Research Institute) with the US National Institutes of Health (2025) analysed over one million electronic health records from the United Kingdom, Wales included, and Finland. Sleep disorders were associated with a higher risk of neurodegenerative disease, and this risk appeared up to 15 years before the formal diagnosis.

A signal that comes before the diagnosis

Alzheimer's and Parkinson's are often diagnosed once the symptoms are already clear. This study adds one thing: sleep disorders show up in health records many years earlier. It is an association seen in large groups of people. It does not show that disturbed sleep causes the disease, nor what will happen to any one person.

According to the authors, the risk linked to sleep disorders is independent of genetic risk for Alzheimer's and Parkinson's, estimated with a polygenic score. In people with low genetic risk, disturbed sleep still weighs: the authors describe it as almost compensating for the missing genetic risk. It remains an association, not proof of a cause.

Which sleep disorders were considered

The disorders considered include obstructive sleep apnoea, insomnia and circadian rhythm disorders.

The authors note that sleep apnoea and poor sleep habits can be treated, for instance with CPAP, and that treating them could reduce the risk. That is a hypothesis still to be tested.

A ring or a watch that tracks sleep records how long and how regularly you sleep; a sleep disorder such as apnoea is diagnosed with a clinical test. The Digital Twin lines up the data your devices write to your phone, such as steps, heart rate and sleep, and shows you how they change over time. It makes no forecasts about your health and it does not diagnose: this research describes groups of people, not you. If your sleep worries you, talk to your doctor.