Objective: Advanced age is associated with prominent impairment in allocentric navigation dependent on the hippocampus. This study examined whether age-related impairment in allocentric navigation and strategy selection was associated with sleep disruption or circadian rest-activity fragmentation. Further, we examined whether associations with navigation were moderated by perceived stress and physical activity.
Method: Sleep fragmentation and total sleep time over the course of 1 week were assayed in younger (n = 42) and older (n = 37) adults via wrist actigraphy. Subsequently, participants completed cognitive mapping and route learning tasks, as well a measure of spontaneous navigation strategy selection. Measurements of perceived stress and an actigraphy-based index of physical activity were also obtained. Circadian rest-activity fragmentation was estimated via actigraphy post-hoc.
Results: Age was associated with reduced cognitive mapping, route learning, allocentric strategy use, and total sleep time (ps < .01), replicating prior findings. Novel findings included that sleep fragmentation increased with advancing age (p = .009) and was associated with lower cognitive mapping (p = .022) within the older adult cohort. Total sleep time was not linearly associated with the navigation tasks (ps > .087). Post-hoc analyses revealed that circadian rest-activity fragmentation increased with advancing age within the older adults (p = .026) and was associated with lower cognitive mapping across the lifespan (p = .001) and within older adults (p = .005). Neither stress nor physical activity were robust moderators of sleep fragmentation associations with the navigation tasks (ps > .113).
Conclusion: Sleep fragmentation and circadian rest-activity fragmentation are potential contributing factors to age effects on cognitive mapping within older adults.
Keywords: circadian rhythms; cognitive mapping; physical activity; route learning; sleep fragmentation.