Chronic insomnia and dementia: More than 16% of the world’s population lives with insomnia, a disorder marked by difficulty falling or staying asleep. A substantial share have chronic insomnia, defined as poor sleep on three or more nights a week for over three months. Prior research has linked insomnia to cardiometabolic disease and mood disorders; new data now point to heightened risks for mild cognitive impairment (MCI) and dementia.
In a study published in Neurology, researchers followed 2,750 cognitively healthy adults (average age 70) for a mean of 5.6 years. About 16% met criteria for chronic insomnia at baseline. Those with chronic insomnia had a 40% greater risk of developing MCI or dementia than participants with non-chronic insomnia, an effect the authors say is comparable to 3.5 extra years of brain ageing and exceeds the risk conferred by some cardiometabolic conditions.
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Participants completed sleep questionnaires, cognitive testing, and brain imaging to assess white matter hyperintensities and beta-amyloid, biomarkers tied to small-vessel disease and Alzheimer’s pathology, respectively. Shorter sleep was associated with more amyloid deposition and greater white matter changes, suggesting parallel Alzheimer’s and cerebrovascular pathways. “Insomnia with reduced sleep was linked to both amyloid and small-vessel disease markers,” said lead author Diego Z. Carvalho, MD, MS (Mayo Clinic), underscoring dual mechanisms of cognitive decline.
Clinicians warned that insomnia remains under-recognised and undertreated, particularly in older adults who may normalise poor sleep. Experts emphasised routine sleep assessment in primary care and geriatrics and highlighted cognitive behavioural therapy for insomnia (CBT-I) as first-line treatment, with digital and app-based options expanding access.
