A comprehensive meta-analysis of 76 longitudinal cohort studies found that multiple sleep disorder types independently raise the risk of cognitive decline and dementia. Insomnia raised dementia risk 13%, while long sleep duration (>8 hours) increased Alzheimer's disease risk by 66%. Excessive daytime sleepiness raised vascular dementia risk by 85%. Sleep-related movement disorders showed the strongest signal, more than doubling vascular dementia risk. Poor sleep quality was linked to a 17–24% increased risk across dementia subtypes. These findings establish sleep as a major modifiable target for dementia prevention, calling for systematic clinical screening and early intervention across all sleep disorder categories.
