RESUMEN
BACKGROUND: Previous studies investigating the relationship between sleep duration and cognitive function in older adults have suggested that longer sleep durations are associated with decreased cognitive performance. AIM: The intent of this study is to determine if performance on the Montreal Cognitive Assessment (MoCA) and the Mini Mental State Exam (MMSE) is associated with self-reported sleep duration in older adults. METHODS: Data from 189 cognitively normal older adults aged 75 and older (mean age 89.29 ± 7.62) and free of severe depression were used for this analysis. Individuals were grouped based on their self-reported hours of sleep (short duration = <7, normal duration = 7, >9, and long duration = ≥9). The Kruskal-Wallis test was used to discern group differences on the MoCA scores, while multinomial logistic regression was used to assess the association between MoCA and MMSE scores and sleep group. RESULTS: The long duration group had significantly lower MoCA scores than the normal duration group (p = 0.02). The short duration group was not significantly different from the normal duration group (p = 0.33). Individuals in the short duration group were more likely to have higher MoCA scores than those in long duration group after adjusting for age, gender, and presence of depressive symptoms [OR 0.86, 95 % CI (0.76, 0.98), p = 0.02]. CONCLUSION: The results of this study suggest that in a group of non-demented, very old subjects, self-reported sleep duration of nine or more hours is associated with decreased cognitive performance on the MoCA in older adults, even after accounting for age, gender, and presence of depressive symptoms.