Sleep-Wake Disturbances and Episodic Memory in Older Adults

Sleep-wake disturbances have been associated with episodic memory loss, but past studies were limited by use of single measures of objective or perceived disturbances. Notably, cognitive reserve and depressive symptoms have been associated with sleep-wake disturbances and poorer episodic memory in older adults. The aims of this study were to determine the relationship between episodic memory and sleep-wake disturbances using objective and perceived measures in older adults and to examine cognitive reserve and depressive symptoms as moderators of this relationship. In this descriptive study, 62 healthy older adults (mean age: 69.9 years; 75.8% women) were recruited from the University of Michigan Clinical Research Program. Objective sleep-wake disturbances were measured by 7-day actigraphy and perceived sleep-wake disturbances by the Pittsburgh Sleep Quality Index and Epworth Sleepiness Scale. Episodic memory was measured by the Hopkins Verbal Learning Test-Revised. Analyses involved Pearson's correlation coefficients and hierarchical multiple regression. Results showed that more objectively measured sleep disruption was associated with poorer episodic memory and more perceived daytime sleepiness was associated with better episodic memory. Cognitive reserve and depressive symptoms were not moderators of this relationship. In this study, the relationship between sleep-wake disturbances and episodic memory differed by type of measure, objective or perceived. Future studies are needed using multiple measures of episodic memory to further understand the sleep-wake disturbances and episodic memory relationship in a larger diverse sample of healthy older adults.