Objective and Subjective Intraindividual Variability in Sleep: Predisposing Factors and Health Consequences

Abstract

Objective We investigated the factors that predispose or precipitate greater intra-individual variability (IIV) in sleep. We further examined the potential consequences of IIV to overall sleep quality and health outcomes, including whether these relationships were found in both self-reported and actigraphy-measured sleep IIV. Methods In Study 1, 699 US adults completed a Sleep Intra-Individual Variability questionnaire and self-reported psychosocial, sleep quality, and health outcomes. In Study 2, 100 university students wore actigraphy and completed psychosocial, sleep, and health surveys at multiple timepoints. Results In cross-sectional analyses that controlled for mean sleep duration, predisposing/precipitating factors to greater IIV were being an under-represented racial/ethnic minority (Study 1: F = 13.95, p < .001; Study 2: F = 7.03, p = .009), having greater stress (Study 2: r values ≥ 0.32, p values ≤ 0.002) or trait vulnerability to stress (Study 1: rs ≥ 0.15, ps < 0.001), and showing poorer time management (Study 1: r = -0.23, p < 0.001; Study 2: rs ≤ -0.26, ps ≤ 0.013). In addition, both studies showed that greater sleep IIV was associated with decreased overall sleep quality, independent of mean sleep duration (Study 1: rs ≥ 0.20, ps < 0.001; Study 2: rs ≥ 0.33, ps ≤ 0.001). Concordance across subjective and objective IIV measures was modest (rs: 0.09-0.35) and similar to concordance observed for subjective-objective mean sleep duration measures. Conclusion Risk for irregular sleep patterns is increased in specific demographic groups and may be precipitated by, or contribute to, higher stress and time management inefficiencies. Irregular sleep may lead to poor sleep quality and adverse health outcomes, independent of mean sleep duration, underscoring the importance of addressing sleep consistency.

Exploring the Interplay Between Stress, Sleep, and Health: A Special Issue Commemorating the Contributions of Dr. Martica Hall

“…We believe Tica would have been pleased to see a single issue addressing topics as diverse as the impact of sleep on cardiovascular health in physicians experiencing burnout (1); the role of biobehavioral rhythm stability in predicting the metabolic syndrome (2); dyadic sleep influences on posttraumatic symptoms among cancer patients and their caregivers (3); and prospective, often bidirectional associations between sleep and psychosocial factors (4–6) and mental health (7,8). Several articles also highlight the dynamic nature of sleep during critical periods across the life span (9) and multidimensional conceptualizations of sleep health (10), ideas and methodologies championed by Tica. We are also quite certain that Tica would have applauded the focus on social determinants of sleep and sleep health disparities (11–14) and the links between sleep and heart rate variability (15,16).…”