| Popis: |
Habitual (i.e., average or typical) sleep duration and sleep efficiency vary widely by demographic characteristics, including age, gender, and racial/ethnic identity. Despite a wealth of studies on demographic patterns in habitual sleep, these results are often based on cross-sectional surveys, which ask participants to retrospectively recall their "typical" or "recent" sleep. Yet, sleep is a highly dynamic behavior and may fluctuate substantially from night-to-night. This intraindividual variability (IIV) in sleep/wake patterns can be captured a multitude of ways, most commonly by using formula-based calculations. Although there is growing attention on the importance of IIV in sleep, findings on demographic differences are still inconclusive, and there are no guidelines for typical values of IIV in sleep. The present study quantitatively synthesized 8 international data sets (N = 2847 participants, 29,832 total days of sleep data), focusing on examining age, gender, and racial/ethnic identity differences in IIV in sleep measured via sleep diaries, actigraphy, and electroencephalography. Sleep duration and sleep efficiency varied widely from night-to-night within people (duration: 64-119 minutes; efficiency: 5-8%). Different metrics of IIV were strongly correlated within and across sleep measurement types. Younger adults had more IIV in diary and actigraphy sleep duration. Gender differences in IIV in sleep were inconsistent, and non-Hispanic/Latinx and White adults had less IIV in sleep compared to other racial/ethnic minority groups. Results emphasize the importance of assessing IIV in sleep, and show that even among healthy sleepers, sleep varies from night-to-night. Like mean sleep, there may also be disparities in IIV in sleep by demographic characteristics, highlighting a need for targeted interventions to stabilize sleep and improve health. |
