Association of sleep timing and sleep variability with health-related outcomes in a sample of Brazilian adolescents

ABSTRACT

Objectives

This cross-sectional study aimed to examine the relationships of sleep timing and sleep variability with depressive symptoms, health-related quality of life (HRQoL), daytime sleepiness, and body mass index (BMI) in adolescents.

Methods

Adolescents from three schools (n = 571, 56% female, 16.3 ± 1.0 years) had their sleep examined by actigraphy, their anthropometrics assessed, and answered a survey. Sleep timing was examined by combining groups of median-dichotomized onset and wakeup times (early onset and early wakeup; early onset and late wakeup; later onset and early wakeup; later onset and later wakeup); sleep variability was based on within-participant standard deviations of onset and wakeup; and sleep duration as the length of time between onset and wakeup. The sleep variables were separated for weekdays and weekend. Mixed linear models were fitted to compare each sleep variable with health-related outcomes.

Results

Higher values of daytime sleepiness were observed in adolescents from the late-early and late-late timing group during the week. Greater sleep midpoint and wakeup variability on weekdays were related with higher daytime sleepiness. Adolescents in the late-late and early-late groups showed higher daytime sleepiness. Increased of all sleep variability variables was related with greater daytime sleepiness. Higher depressive symptoms scores were found among adolescents in the late-early subgroup and with the increase of sleep variability. Participants with greater sleep onset variability and sleep midpoint variability reported less HRQoL.

Conclusions

Not only sleep duration, but sleep timing and variability also relate to health outcomes, and should be addressed by policies and interventions among adolescents.

Acknowledgments

We want to thank the participants and school staff for their voluntary participation and contribution to the study. Furthermore, we want to express our gratitude to the Research Group in Physical Activity and Health colleagues who helped us in data collection.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/15402002.2023.2207699

Additional information

Funding

This work was supported by the Brazilian National Council for Scientific and Technological Development (CNPq) (406258/2018-0), the Coordination for the Improvement of Higher Education Personnel (CAPES) (Finance code 001), and Research Support Foundation of the State of Amazonas (FAPEAM) to support this study.