Sleep duration and cognition in middle-aged and older European adults: cross-sectional SHARE analysis
In a cross-sectional analysis of SHARE waves 8 and 9 (2019–2022), sleep duration of 10 hours or more and daytime napping were each associated with lower cognition among community-dwelling middle-aged and older Europeans; the authors call for research on clinical significance and causality. [1]
Automatic summary · not editorially reviewed
The key findings
The analysis pooled SHARE waves 8 and 9 (2019–2022) and examined cross-sectional associations between sleep-related issues and cognition in community-dwelling middle-aged and older adults. [1]
Of 88,889 interviews, 7% were categorized as probable dementia, 12% as cognitive impairment no dementia and 81% as normal cognition. [1]
After adjustment, only sleep duration of 10 hours or more and daytime napping remained statistically significantly associated with cognition; the authors call for research on clinical significance and causal relationships. [1]
The source at a glance
- Study type / format
- Cross-sectional analysis of pooled survey waves (abstract)
- Population / context
- Community-dwelling middle-aged and older adults in the SHARE study, waves 8 and 9 (2019–2022).
- Summary based on
- Study abstract
- Original publication
- September 3, 2026
SHARE waves 8–9 sleep and cognition sample
The source describes the Survey of Health, Ageing and Retirement in Europe (SHARE), a longitudinal multi-country study of community-dwelling middle-aged and older adults. This analysis pooled waves 8 and 9 (2019–2022) and examined the cross-sectional association between sleep-related issues and cognition. Subjective sleep data came from both waves; objective data were available from wave 8. Cognition was assessed with the SHARE Cognitive Instrument (SHARE-Cog). Participants were grouped as probable dementia, cognitive impairment no dementia (CIND) or normal cognition.
Supporting source [1]
Long sleep and napping linked to lower cognition
88,889 interviews were included (55% female; mean age 68.88): 7% probable dementia, 12% CIND and 81% normal cognition. Unadjusted, sleep duration and cognition showed an inverted U-shaped association. After adjustment for potential confounders, only the association with sleep durations of 10 hours or more remained statistically significant. Cognitive impairment was significantly associated with recent trouble sleeping, weekly sleep medication use and daytime napping; after adjustment, only the daytime napping association remained statistically significant.
Supporting source [1]
Cross-sectional design limits causal reading
The authors conclude that the analysis confirmed an association between sleep duration of 10 hours or more and lower cognitive scores among community-dwelling middle-aged and older Europeans, and that cognitive impairment was also associated with daytime napping. They state that further research is needed to understand the clinical significance of these findings and to establish the underlying causal relationships. The design is cross-sectional, so the reported associations do not show that sleep causes cognitive differences or vice versa.
Supporting source [1]
How to interpret this
Abstract only; the full text was not reviewed. This is a cross-sectional analysis, so associations do not establish causation. Objective sleep data were available only from wave 8. The authors state that further research is needed on clinical significance and causal relationships.
Based on the study abstract; the full paper, tables and supplementary data were not reviewed.
Source & supporting passages
Crowley P, O'Donovan MR, Flanagan E, O'Caoimh R. · europepmc.org · September 3, 2026