Intra-individual daily and yearly variability in actigraphically recorded sleep measures: The CARDIA study

Department of Health Studies, University of Chicago, 5841 S. Maryland Ave, MC 2007, Chicago, IL, USA.
Sleep (Impact Factor: 4.59). 07/2007; 30(6):793-6.
Source: PubMed


To describe the day-to-day and year-to-year variation in sleep characteristics among early middle-aged adults.
Participants wore an Actiwatch (Mini Mitter, Inc) for 3 days on two occasions approximately 1 year apart.
N = 669 participants aged 38-50 years from the Chicago site of the Coronary Artery Risk Development in Young Adults (CARDIA) cohort study.
Sleep measures included sleep duration, sleep latency, sleep efficiency, and time in bed. For each sleep parameter, total variance was decomposed into between-subject variance, within-subject variance from day to day, and within-subject variance from year to year. The standard deviation was calculated from the variance. Analysis yielded a within-subject daily standard deviation (SD) of 1.26 hours and a within-subject yearly SD of 0.39 hours for sleep duration. Daily SD was 30.7 minutes and yearly SD was 6.3 minutes for within-subject variability of sleep latency. Daily SD was 8.4% and yearly SD was 2.7% for within-subject variability of sleep efficiency. Finally, daily SD was 1.31 hours and yearly SD was 0.52 hours for within-subject variability of time in bed.
For each of the 4 sleep characteristics, nightly variability was much greater than yearly variability, meaning sleep behavior changes little in one year in this cohort of early middle-aged adults, despite large daily fluctuations. These results have important methodological implications, including that single-day measures of sleep may not accurately reflect habitual behavior.

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Available from: Kristen L Knutson, Sep 29, 2015
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    • "Dillon Q3 and colleagues (2014) identified that IIV in sleep was actually lower at older ages. Furthermore, compared with the literature support for IIV in sleep [13] [18] [27], less is known about IIV of pre-sleep arousal, and how pre-sleep arousal IIV may vary across ages. If pre-sleep arousal and sleep show considerable IIV, the traditional analytic approach of relying on the examination of mean values, or single measurements, may not be the most appropriate level of measurement for these variables [10]. "
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    ABSTRACT: Intraindividual variability is an often understudied aspect of health outcomes research that may provide additional, complementary information to average values. The current paper aims to further our understanding of intraindividual variability in health research by presenting the results of a daily diary study of sleep and pre-sleep arousal. Pre-sleep arousal is often implicated in poor sleep outcomes, although the arousal–sleep association is not uniform across age groups. The examination of intraindividual variability in different age groups may provide a more complete understanding of these constructs, which, in turn, can inform future research. The overall objectives of the current study are to quantify the amount of intraindividual variability in pre-sleep arousal and sleep and to examine age differences in this variability. A sample of older (n=50) and younger (n=50) adults recruited from North Central Florida and online completed 14-consecutive-day diaries assessing pre-sleep arousal and sleep outcomes. Significant age differences were found for sleep and pre-sleep arousal; older adults displayed poorer, more variable sleep for the majority of sleep outcomes, and higher levels of pre-sleep arousal than younger adults. The high amount of intraindividual variability has implications for the assessment of pre-sleep arousal and sleep across age groups.
    Sleep Science 03/2015; 34(1). DOI:10.1016/j.slsci.2015.02.005
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    • "Sleep fragmentation scores, or a measure of the restlessness of sleep, were estimated by summing the percentage of movement time with the percentage of time spent immobile for ≤1 min. A previous report found high continuity in the values recorded between the two waves for sleep duration [15]. Further information on the methods used in the CARDIA Sleep Study have been described [9]. "
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    ABSTRACT: Objective To determine the association between objectively measured sleep and 10-year changes in estimated glomerular filtration rate (eGFR). Methods From 2003 to 2005, an ancillary sleep study was conducted at the Chicago site of the Coronary Artery Disease in Young Adults (CARDIA) study. Community-based black and white adults (aged 32–51 years) wore a wrist actigraph up to six nights to record sleep duration and fragmentation. Sleep quality was measured with the Pittsburgh Sleep Quality Index (PSQI). Participants without history of cardiovascular or chronic kidney diseases, proteinuria, or hypertension at the 2000–2001 CARDIA examination were followed over 10 years (n = 463). eGFR was estimated from serum creatinine (eGFRCr) at the 2000–2001, 2005–2006, and 2010–2011 CARDIA examinations, whereas cystatin-C-estimated eGFR (eGFRCys) was measured at the 2000–2001 and 2005–2006 examinations. Generalized estimating equation regression and linear models estimated the associations of each sleep parameter with changes in eGFRCr and eGFRCys, controlling for cardiovascular and renal risk. Results Sleep parameters were not related to 5-year change in eGFRCys. However, each 1 h decrease in sleep duration was significantly associated with a 1.5 mL/min/1.73 m2 higher eGFRCr [95% confidence interval (CI), 0.2−2.7], and each one-point increase in PSQI was significantly associated with a 0.5 mL/min/1.73 m2 higher eGFRCr (95% CI, 0.04−0.9) over 10 years. Conclusion In this community-based sample, shorter sleep and poorer sleep quality were related to higher kidney filtration rates over 10 years.
    Sleep Medicine 09/2014; DOI:10.1016/j.sleep.2014.05.021 · 3.15 Impact Factor
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    • "Troxel et al. (2007) "
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    ABSTRACT: Objective: Relations between interpartner psychological conflict (IPC) and the sleep of men and women were examined, and depression and anxiety symptoms were assessed as intervening variables of these associations. Method: Participants were 135 cohabiting or married couples. The mean age was 36.50 (SD = 5.93) for women and 39.37 (SD = 7.33) for men. Most women (76%) and men (78%) were European American (EA) and the rest were predominantly African American (AA); there was a wide socioeconomic representation. Men and women reported on IPC used by their partner against them. Sleep was examined objectively with actigraphs, and multiple sleep quantity and quality measures were derived. Results: Dyadic path analysis in which both actor and partner effects were assessed was conducted. For women, greater IPC by the partner was related to elevated levels of anxiety, which in turn was associated with shorter sleep duration and worse sleep efficiency; anxiety was an intervening variable. For men, IPC by the partner was related to greater symptoms of anxiety and depression; the latter was an intervening variable linking IPC with sleep quality (lower efficiency, longer latency). Some partner effects were observed and indicate that for both men and women, one's perpetration of IPC is related to increased anxiety in the partner, which in turn is related to longer sleep latency for the actor. Conclusion: Results build on this scant literature, and using objective well-validated measures of sleep highlight the importance of relationship processes and mental health for the sleep of men and women.
    Health Psychology 04/2013; 32(10). DOI:10.1037/a0031786 · 3.59 Impact Factor
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