Self-report and actigraphy measures of sleep and domain-specific cognitive performance in older adults

Poor sleep is associated with worse cognitive function in older adults. However, nuanced associations between sleep and cognition might be masked by the multidimensional nature of sleep which requires multiple approaches (e.g., self-report and actigraphy) to gain meaningful insight. We investigated associations of sleep with cognition and hypothesized that the most consistent association would be between self-reported sleep duration and actigraphy-measured wake after sleep onset (WASO). We utilized baseline data from the Investigating Gains in Neurocognition in an Intervention Trial of Exercise study. Cognitively unimpaired older adults (n=589, aged 65-80) completed a comprehensive cognitive assessment with generation of five domain-specific cognitive composite scores. Sleep was measured via the Pittsburgh Sleep Quality Index (PSQI) and 24-h actigraphy (GT9X Link). Greater actigraphy WASO and shorter self-reported sleep duration were associated with poorer performance in all five cognitive domains (β_{[range: WASO]} = -0.14 to -0.19, all p<0.05; β_{[range: duration]} = 0.08-0.15, all p<0.05). Shorter actigraphy sleep duration was also associated with poorer EF/attentional control (β=0.09, p=0.020) and processing speed (β=0.10, p=0.013). Actigraphy and self-reported sleep were more strongly associated with episodic memory in older (74 years) and younger (66 years) individuals, respectively. Actigraphy-derived WASO was consistently and robustly associated with cognitive performance. Additionally, our results suggest that self-reported sleep duration provides insight into sleep behaviors related to brain health (e.g., long periods of still wakefulness), beyond actigraphy-measured sleep duration. Thus, both self-report and actigraphy measures of sleep provide critical and unique information for interpreting relationships with cognitive performance.