Dr Atul Dhingra and Dr Sanjay Kalra
A new study published in Neurology on September 10, 2025, warns that older adults suffering from chronic insomnia face a 40% higher risk of developing mild cognitive impairment (MCI) or dementia compared to those without sleep difficulties. The findings suggest that long-term insomnia may accelerate brain aging by the equivalent of 3.5 years, underscoring the role of sleep in protecting cognitive health.
This study was conducted with 2,750 cognitively healthy older adults from the Mayo Clinic Study of Aging, mean age 70 years, with or without chronic insomnia to investigate the association between chronic insomnia and incident cognitive impairment. Chronic insomnia was defined as difficulty in sleeping for at least three nights a week for ≥3 months. Almost half (49.2%) of the study group was female. The participants were followed for a median duration of 5.6 years. The sleep duration, whether more or less than usual during the past 2 weeks, was evaluated at baseline. They also underwent annual neuropsychological evaluation and brain imaging to look for amyloid plaques (amyloid-PET burden) and white matter hyperintensities on magnetic resonance imaging (MRI) scans.
This study was conducted with 2750 cognitively healthy older adults from the Mayo Clinic Study of Aging, mean age 70 years, with or without chronic insomnia to investigate the association between chronic insomnia and incident cognitive impairment. Chronic insomnia was defined as difficulty in sleeping for at least three nights a week for ≥3 months. Almost half (49.2%) of the study group was female. The participants were followed for a median duration of 5.6 years. The sleep duration, whether more or less than usual during the past 2 weeks, was evaluated at baseline. They also underwent annual neuropsychological evaluation and brain imaging to look for amyloid plaques (amyloid-PET burden) and white matter hyperintensities on magnetic resonance imaging (MRI) scans.
Overall, 16% of the participants had chronic insomnia. During the course of the study, 14% of those with chronic insomnia developed mild cognitive impairment or dementia versus 10% without insomnia.
Individuals with insomnia had 40% higher likelihood of developing mild cognitive impairment or dementia than those without insomnia with hazard ratio (HR) of 1.40. Insomnia was also linked to a faster annual decline in global cognitive scores (−0.011 per year). Insomnia accompanied by reduced sleep was associated with poorer baseline cognitive performance (β = -0.211), greater white matter hyperintensity (WMH) burden (β = 0.147), and higher amyloid-PET burden (β = 10.5).
Participants with insomnia who reported sleeping more than usual showed fewer white matter hyperintensities at baseline (β = -0.142). In contrast, those who reported getting less sleep than usual were more likely to have lower cognitive test scores at the beginning of the study and they also had more white matter hyperintensities and amyloid plaques. Insomnia was not associated with how fast the white matter hyperintensities or amyloid accumulated. Among those with insomnia, no association was noted between use of hypnotics and cognitive performance (β = 0.016) or risk of incident cognitive impairment (HR 0.94).
Participants carrying the APOE ε4 gene, known to increase the risk of Alzheimer’s disease, showed marked declines in memory and cognitive function.
This study demonstrates that chronic insomnia may damage the brain through accumulation of amyloid plaques associated with Alzheimer’s disease and small vessel changes indicated by the presence of white matter hyperintensities. Although it does not prove causation, these findings add credence to the need to treat chronic insomnia not only for better quality sleep but also to protect brain health with aging. As the authors stated, “Sleep isn’t just about rest – it’s also about brain resilience.”
Reference
1. Carvalho DZ, et al. Associations of chronic insomnia, longitudinal cognitive outcomes, amyloid-PET, and white matter changes in cognitively normal older adults. Neurology. 2025 Oct 7;105(7):e214155. doi: 10.1212/WNL.0000000000214155.