Habitual Sleep, Reasoning, and Processing Speed in Older Adults with Sleep Complaints

Abstract

The relationship between habitual sleep and cognition in older adults with sleep complaints is poorly understood, because research has focused on younger adults, used experimental or retrospective quasi-experimental designs, and generally produced equivocal results. Prospective studies using sleep diaries are rare, but may provide important insights into this relationship as they offer greater ecological validity and allow for examination of the impact of night-to-night variability in sleep (an often overlooked aspect of sleep) on cognitive performance. Seventy-two older adults (Mage = 70.18 years, SDage = 7.09 years) completed fourteen consecutive days of sleep diaries and paper/pencil self-administered cognitive tasks, including measures of processing speed (Symbol Digit) and reasoning (Letter Series). Regression analyses revealed increased average total wake time (TWT) during the night was associated with higher Symbol Digit scores, β = 0.45, P < 0.05. Night-to-night variability in either total sleep time (TST) or TWT was not associated with either cognitive measure. Implications and potential explanations for these initially counterintuitive findings are discussed.

Chronic Pain, Sleep, and Cognition in Older Adults With Insomnia: A Daily Multilevel Analysis

“…Although sleep did not negatively affect SDMT performance in individuals without a history of chronic pain, our daily findings for this group are consistent with our previous results showing that poor sleep (ie, greater total wake time) is associated with better average processing speed and selective attention performance over 2 weeks of baseline. 10 Specifically, in the current study, we found that greater self-reported WASO led to better next-day performance on SDMT. It is possible that increased WASO at night may lead to a hyperaroused state 11 which then in turn leads to better next-day cognitive performance in those without a history of chronic pain, at least on a cognitive task that measures lower level processing.…”

“…7,8 A study examining sleep quality and cognitive performance in older adults with insomnia found that poor sleep quality was associated with worse performance on tests measuring on executive functions (eg, working memory, attentional set shifting, abstract reasoning), but was not associated with episodic memory or processing speed. 9 Interestingly, we also previously reported results showing that longer total wake time was associated with better performance on a sustained attention and processing speed task, 10 suggesting that increases in nighttime wakefulness may translate to a state of hyperarousal that provides a benefit to lower level cognitive processing. 11 However, these findings represented aggregate patterns of average performance across 2 weeks rather than daily patterns of association and did not consider the effects of chronic pain.…”

Sleep, Cognition, and Normal Aging

“…Several researchers have noted this “functional weakening” possibility (Edinger et al, 2000; Kronholm, 2012; McCrae et al, 2012; Pace-Schott & Spencer, 2011; Schmidt, Peigneux, & Cajochen, 2012; Scullin, 2013; Spiegel et al, 1986), and some supportive evidence was observed in most of the reviewed literatures. Though functional weakening remains relatively unexplored, this view uniquely predicts that increasing the quantity of sleep in older adults is unlikely to restore cognitive abilities because age-related neurobiological changes (e.g., neural atrophy, decreased plasticity, nocturnal hypoxia, neuroendocrine changes, altered neuromodulation) that are presumably necessary to support sleep-specific cognitive processes will still be impaired.…”

“…Increased nighttime awakenings were associated with poor memory in one small sample study (Mary, Schreiner, & Peigneux,, 2013; see also Sampaio, Sampaio, Yamada, Tsuboyama, & Arai, 2013), but puzzlingly, at least four studies have found the opposite pattern (Foley et al, 1995; Maggi et al, 1998; McCrae, Vatthauer, Dzierzewski, & Marsiske, 2012; Miller et al, 2014). The peculiar finding that greate wake time at night could be related to better cognitive performance in older adults is in notable contrast to the findings in young and middle- aged adults.…”

The association between insomnia-related sleep disruptions and cognitive dysfunction during the inter-episode phase of bipolar disorder

“…Insomnia coupled with short sleep duration (<6 hours) also appears to have a greater impact on cognitive dysfunction when compared to insomnia with normal sleep duration and healthy sleep patterns (Fernandez-Mendoza et al, 2010). Only one study has examined the impact of sleep variability on cognition, (McCrae et al, 2012) revealing that night-to-night variability in sleep duration and total wake time did not predict performance on a processing speed or an executive functioning task in older adults.…”