| Abstract: | This study examined whether sleep duration and excessive daytime sleepiness (EDS) are related to cognitive decline among community‐dwelling older adults with intact cognition at baseline, using 4‐year longitudinal data. A total of 3,151 community‐dwelling older individuals aged ≥65 years were studied. They were assessed for cognitive function, including memory, attention, executive function and processing speed. Cognitive impairment was defined based on a score >1.5 standard deviations below the age‐ and education‐specific mean. Cognitive decline was defined in one or more cognitive tests at follow‐up. Self‐reported sleep duration (short, ≤6.0 hr; medium, 6.1–8.9 hr; long, ≥9.0 hr) and EDS at first‐wave examination were assessed and logistic regression analyses were used to examine the associations of sleep duration and EDS with cognitive status at second‐wave examination. The incidence of cognitive decline differed significantly among the sleep‐duration groups (short, 15.9%; medium, 11.9%; long, 20.1%; p = 0.001). The prevalence of having EDS was 13.1%, which was associated with a higher rate of cognitive decline than having no EDS (18.9% vs. 12.5%, p = 0.004). Long sleep duration compared with medium sleep duration (OR, 1.50; 95% CI, 1.05–2.13) and EDS (1.43; 1.01–2.03) independently impacted the incidence of cognitive decline. The results were similar after multiple imputations (long, 1.68, 1.12–2.52; EDS, 1.55, 1.05–2.29). In conclusion, our study revealed that both long sleep duration and EDS were independent risk factors associated with cognitive decline after 4 years among older adults. |
