title: Variety is the Spice of Life: A Microlongitudinal Study Examining Age Differences in Intraindividual Variability in Daily Activities in Relation to Sleep Outcomes.
abstract: OBJECTIVE
  The relative importance of mean timing of daily activities versus intraindividual variability in the timing of daily activities in relation to health outcomes such as sleep has yet to be established. Furthermore, age-related changes in sleep could affect this relationship. The study objective was to examine the extent that intraindividual variability in the timing of daily activities is associated with sleep outcomes in younger and older adults.
  
  
  METHODS
  A microlongitudinal observational study design was used with 14 consecutive days of diaries in community-dwelling younger and older adults. 50 younger and 50 older adults completed daily assessments of activities and sleep. Three activities (going outside, starting work, and eating dinner) and 5 sleep (sleep onset latency, wake time after sleep onset, number of awakenings, total sleep time, and sleep quality rating) variables were used in the analyses.
  
  
  RESULTS
  Hierarchical regressions revealed variability in the timing of daily activities significantly predicted sleep, beyond mean timing of activities, for 4 of 6 models. Results differed depending on the type of activity and age group.
  
  
  CONCLUSIONS
  Intraindividual variability, not mean timing of daily activities, best-predicted sleep outcomes. Variability was associated with positive sleep outcomes for older, but not younger adults.
authors: Department of Psychology, University of Alabama, Tuscaloosa. nddautovich@as.ua.edu.
authors: Natalie D
authors: ND
authors: Dautovich
authors: Department of Psychology, University of Alabama, Tuscaloosa.
authors: Kristy D
authors: KD
authors: Shoji
authors: Department of Clinical and Health Psychology, University of Florida, Gainesville.
authors: Christina S
authors: CS
authors: McCrae
mesh_terms: D000203:Activities of Daily Living; D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D012890:Sleep / Q000502:physiology*; D013997:Time Factors; D055815:Young Adult
keywords: Circadian; Intraindividual variability; Mircrolongitudinal; Older adults; Sleep.