Divergent effects of sleep efficiency and sleep medication on episodic memory in mid to late life.

Objectives: Different aspects of sleep quality are known to decline with age, and these changes have been shown to impact performance across multiple cognitive domains. However, despite a growing body of literature, the impact of changes to quality of sleep on episodic memory remains elusive, with some studies finding effects and others failing to find a relation. Methods: In this study, participants [N = 173, mean age = 65.30, range = [45-88]], completed the Pittsburgh Sleep Quality Index as well as three episodic memory tests (verbal and visual episodic memory and pattern separation). Results: We found that worse sleep efficiency was associated with worse overall episodic memory. Further, medication use had a positive effect on verbal, pattern separation, and overall episodic memory. Findings occurred in an age-dependent manner. Conclusions: These results underscore the complexity of sleep-memory interactions and suggest that certain aspects of episodic memory may be more sensitive to specific components of sleep quality than others, particularly as individuals age.