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

Abstract

Objectives This study examined associations between various cognitive domains and sleep discrepancy (self-reported versus objectively measured sleep), and evaluated interactive associations with insomnia status (non-insomnia versus insomnia). Method 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 ProfilerTM during the 7-day period), and completed cognitive tasks (NIH Toolbox-Cognition Battery) measuring attention and processing speed, working memory, inhibitory control, cognitive flexibility, and episodic memory. The sleep diary variable corresponding to same one-night of PSG was used to calculate the sleep discrepancy (diary minus PSG parameter) variables for total sleep time, 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 total sleep time and sleep efficiency. In those with insomnia, worse working memory was associated with shorter self-reported total sleep time (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.