Sleep Discrepancy, Sleep Complaint, and Poor Sleep Among Older Adults

ADULTS aged more than 65 years make up 13% of the total U.S. population and have the highest rates of sleep disturbance for any age group (Ohayon, Carskadon, Guilleminault, & Vitiello, 2004). Chronic insomnia, defined as difficulty initiating or maintaining sleep, waking prematurely, or feeling unrefreshed upon awakening accompanied by sleep complaints lasting at least 6 months (National Institutes of Health, 2005), is among the most common and costly sleep disturbance in late life. Disturbed sleep is related to daytime consequences in older adults including decreased quality of life, cognitive difficulties, increased depression symptoms, and functional limitations (Buysse, Germain, & Moul, 2005; Nebes, Buysse, Halligan, Houck, & Monk, 2009; Newman, Enright, Manolio, Haponik, & Wahl, 1997). Epidemiological studies that estimate the prevalence of insomnia among older adults (~30%) is up to twice that of younger populations (Nau, McCrae, Cook, & Lichstein, 2005). Even when insomnia is absent, aging is often accompanied by declines in indices of sleep quality including sleep continuity, depth, and night-to-night consistency (Boselli, Parrino, Smerieri, & Terzano, 1998; Nau et al., 2005). There is evidence that some changes in sleep quality are more related to declines in physical health than age specifically, suggesting a gradual decline in sleep quality from through middle age, stabilization around retirement, and a further decline in sleep quality related to physical health in older adulthood (Lemola & Richter, 2012). There is intragroup variability in age-related sleep changes and variability in older adults’ perceptions of sleep. For example, some older individuals spend relatively little time trying to fall asleep and have minimal wake time during the night yet complain of poor sleep initiation or maintenance. Conversely, some individuals evidence considerable sleep initiation or maintenance problems consistent with an insomnia diagnosis (i.e., >30min trying to fall asleep or return to sleep) but report no complaints. This pattern is observed when comparing insomnia symptoms to insomnia complaints in older adult men and women. Interestingly, although older adult men experience greater age-related changes in objectively measured sleep onset latency (SOL), older adult women have higher rates of sleep complaints (Vitiello, Larsen, & Moe, 2004). It is possible that age-related changes in sleep predispose older adults to develop insomnia symptoms, but without a subjective sleep complaint, a diagnosis of insomnia is unwarranted. Therefore, the perception of age-related sleep changes may be a primary factor in determining which individuals have insomnia complaints and ultimately meet criteria for insomnia in late life. Adding complexity is the emergence of decreased correspondence between subjective accounts of sleep and objective measures of sleep (Spiegel, 1981). Both objective and subjective measures support documented age-related sleep changes (Buysse et al., 1991), yet these variables tend to correlate poorly at the daily level (Haimov, Breznitz, & Shiloh, 2006; McCrae et al., 2005; Spiegel, 1981). These different methods of measurement may capture unique aspects of sleep with differential predictive value in relation to daytime functioning and health in aging individuals. Subjective methods of measuring sleep (i.e., daily sleep diaries) play a major role in sleep research but have been critiqued for their inability to replicate the findings of objective measures of sleep (i.e., PSG and actigraphy; Haimov et al., 2006). The characterization of discrepancy between objective and subjective measures as error is unfortunate because discrepancy may represent meaningful phenomena. Indeed, the utility of sleep discrepancy between actigraphy and self-report has been previously documented among older adults (McCrae et al., 2005). A comparison of these measures demonstrated that sleep complaint and symptom severity were able to be distinguished among groups of older adults based on the correlation between actigraphy and self-report (McCrae et al., 2005). It was found that in predicting concordance between actigraphy- and self-report-measured sleep, self-reported complaint about sleep was more important than magnitude of insomnia symptoms. Sleep discrepancy, defined as the differences between objective and subjective measures of sleep, has been previously observed among older adults and is particularly common among older adults with sleep complaints (Kay, Dzierzewski, Rowe, & McCrae, 2013). In younger samples, sleep discrepancy is thought to predispose, precipitate, or perpetuate insomnia (Perlis, Giles, Mendelson, Bootzin, & Wyatt, 1997). However, the relationship between sleep discrepancy and insomnia remains understudied among older adults. This study seeks to advance the literature by investigating the patterns and clinical correlates of sleep discrepancy among older adults. This study investigated sleep discrepancy in older adults during two distinct sleep periods: the initial sleep attempt, also called SOL, and also during unwanted awake time during the night, called wake after sleep onset (WASO). The primary aim was to characterize the magnitude and the frequency of discrepancy among older adults depending on whether insomnia symptoms in sleep initiation or maintenance were reported and whether there was an insomnia complaint. We hypothesized that older adults with insomnia symptoms (>30min of SOL or WASO) and a sleep complaint would have greater sleep discrepancy than older adults without a sleep complaint but with comparable levels of insomnia symptoms. We further predicted that older adults with a sleep complaint would have greater discrepancy particularly during WASO, as this aspect of sleep tends to be most disturbed for older adults (Foley et al., 1995). Identifying differences across complaint status and sleep onset or maintenance serves to determine whether sleep discrepancy is more related to the complaint aspect of insomnia or to quantifiable sleep differences among older adults.