Sleep Disorders May Signal Neurodegenerative Risk Years Before Diagnosis, Study Finds

Researchers analyzed over one million anonymized electronic health records spanning two decades (1999–2018) from national biobanks in Wales, the UK, and Finland. They examined the link between clinically diagnosed sleep disorders, such as insomnia, sleep apnea, and other circadian rhythm disturbances, and later development of neurodegenerative diseases.

The study used ICD-10 codes to classify sleep and neurodegenerative diagnoses, ensuring that only clinically recognized conditions were included. It also employed statistical models adjusted for age, sex, and genetic risk scores to isolate the specific influence of sleep-related factors.

The study revealed the following findings:

• Individuals with sleep disorders had a significantly higher likelihood of developing neurodegenerative diseases (NDDs).
• Hazard ratios ranged from 1.3 for Parkinson’s disease to 5.11 for dementia, indicating up to a fivefold increase in neurodegeneration risk due to sleep issues.
• These associations were observed 5 to 15 years before the onset of symptoms, suggesting sleep disturbances may serve as early warning signs.
• The increased risk was evident even in individuals without a genetic predisposition to NDDs.
• Sleep disorders raise the risk of Alzheimer’s disease independently of genetic factors.
• For Parkinson’s disease, an interaction between genetic susceptibility and sleep disturbances was noted.
• Non-organic sleep disturbances, such as nightmares and substance-unrelated insomnia, were linked to a 67% higher risk of dementia and more than double the risk of vascular dementia.
• Sleep apnea was associated with elevated risks of dementia (HR 1.34), vascular dementia (HR 1.44), amyotrophic lateral sclerosis (HR 1.47), and Parkinson’s disease (HR 1.17).

These insights highlight the importance of addressing sleep health as part of strategies aimed at preventing or delaying neurodegeneration. Given that many sleep disorders are modifiable and treatable, early identification and intervention could offer a practical approach to protecting long-term cognitive health.

Although the data predominantly involved European populations and relied solely on electronic health records, the study provides robust evidence supporting the link between sleep and neurological decline. It highlights the potential for sleep evaluations to serve as accessible, non-invasive tools for identifying individuals at elevated risk for neurodegenerative diseases, especially those without strong genetic predispositions.

"Ultimately, the findings point toward a compelling case for integrating sleep disorder assessments into routine clinical care to promote healthier aging and possibly mitigate the burden of dementia and related conditions," the authors concluded.

Reference:

Simmonds, E., Levine, K. S., Han, J., Iwaki, H., Koretsky, M. J., Kuznetsov, N., Faghri, F., Solsberg, C. W., Schuh, A., Jones, L., Blauwendraat, C., Singleton, A., Leonard, H. L., & Nalls, M. A. (2025). Sleep disturbances are risk factors for neurodegeneration later in life. Npj Dementia, 1(1), 1-10. https://doi.org/10.1038/s44400-025-00008-0