Subjective-Objective Sleep Discrepancy in a Predominately White and Educated Older Adult Population: Examining the Associations With Cognition and Insomnia

Objectives: This study examined associations between various cognitive domains and sleep discrepancy (self-reported vs objectively measured sleep), and evaluated interactive associations with insomnia status (non-insomnia vs insomnia).

Methods: Older adults (N = 65, Mage = 68.72, SD = 5.06, 43 insomnia/22 non-insomnia) aged 60+ reported subjective sleep (7 days of sleep diaries), objective sleep assessment (one-night polysomnography, PSG, via Sleep Profiler during the 7-day period), and completed cognitive tasks (National Institutes of Health Toolbox-Cognition Battery) measuring attention and processing speed, working memory, inhibitory control, cognitive flexibility, and episodic memory. The sleep diary variable corresponding to the same one night of PSG was used to calculate the sleep discrepancy (diary minus PSG parameter) variables for total sleep time (TST), sleep onset latency, wake after sleep onset, and sleep efficiency. Regression analyses determined independent and interactive (with insomnia status) associations between cognition and sleep discrepancy, controlling for age, sex, apnea-hypopnea index, and sleep medication usage.

Results: Working memory interacted with insomnia status in associations with sleep discrepancy related to TST and sleep efficiency. In those with insomnia, worse working memory was associated with shorter self-reported TST (p = .008) and lower sleep efficiency (p = .04) than PSG measured.

Discussion: In older adults with insomnia, worse working memory may be a contributing factor to sleep discrepancy. Future investigations of underlying neurophysiological factors and consideration of other objective sleep measures (actigraphy) are warranted. Prospective findings may help determine whether sleep discrepancy is a potential marker of future cognitive decline.