Earlier bedtimes and more sleep displace sedentary behavior but not moderate-to-vigorous physical activity in adolescents

Kendra N Krietsch; Kara M Duraccio; Nanhua Zhang; Brian E Saelens; Taylor Howarth; Angela Combs; Dean W Beebe

doi:10.1016/j.sleh.2022.01.003

Earlier bedtimes and more sleep displace sedentary behavior but not moderate-to-vigorous physical activity in adolescents

Sleep Health. 2022 Jun;8(3):270-276. doi: 10.1016/j.sleh.2022.01.003. Epub 2022 Apr 21.

Authors

Kendra N Krietsch¹, Kara M Duraccio², Nanhua Zhang³, Brian E Saelens⁴, Taylor Howarth⁵, Angela Combs⁶, Dean W Beebe⁷

Affiliations

¹ Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA; Department of Psychology, St. Louis Children's Hospital, St. Louis, Missouri, USA; Department of Clinical Pediatrics, Washington University, St. Louis, Missouri, USA. Electronic address: kendra.krietsch@bjc.org.
² Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA; Department of Psychology, Brigham Young University, Provo, Utah, USA.
³ Division of Biostatistics and Epidemiology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
⁴ Seattle Children's Research Institute and Departments of Pediatrics and Psychiatry and Behavioral Sciences, University of Washington, Seattle, Washington, USA.
⁵ Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA.
⁶ Department of Psychology, University of Cincinnati College of Arts and Sciences, Cincinnati, Ohio, USA.
⁷ Division of Behavioral Medicine and Clinical Psychology, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA; Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.

PMID: 35461788
DOI: 10.1016/j.sleh.2022.01.003

Abstract

Objectives: Correlational models suggest increased cardiometabolic risk when sleep replaces moderate-to-vigorous (but not sedentary or light) physical activity. This study tested which activity ranges are impacted by experimentally altering adolescents' bedtime.

Method: Adolescents completed a 3-week within-subjects crossover experiment with 5 nights of late bedtimes and 5 nights early bedtimes (6.5- and 9.5-hours sleep opportunity, respectively). Experimental condition order was randomized. Waketimes were held constant throughout to mimic school start times. Sleep and physical activity occurred in the natural environments, with lab appointments following each 5-day condition. Waist-worn accelerometers measured physical activity and sedentary behavior. Wrist-worn actigraphs confirmed sleep condition adherence. Wilcoxon tests and linear mixed effects models compared waking activity levels between conditions and across time.

Results: Ninety healthy adolescents (14-17 years) completed the study. When in the early (vs. late) bedtime condition, adolescents fell asleep 1.96 hours earlier (SD = 1.08, d = 1.82, p < .0001) and slept 1.49 hours more (SD = 1.01, d = 1.74, p < .0001). They spent 1.68 and 0.32 fewer hours in sedentary behavior (SD = 1.67, d = 1.0, p < .0001) and light physical activity (SD = 0.87, d = 0.37, p = .0005), respectively. This pattern was reflected in increased proportion of waking hours spent in sedentary and light activity. Absolute and proportion of moderate-to-vigorous physical activity did not differ between conditions (d = 0.02, p = .89; d = 0.14, p = .05, respectively).

Conclusions: Inducing earlier bedtimes (allowing for healthy sleep opportunity) did not affect moderate-to-vigorous physical activity. Alternatively, later bedtimes (allowing for ≤ 6.5 hours of sleep opportunity, mimicking common adolescent school night sleep) increased sedentary behavior. Results are reassuring for the benefits of earlier bedtimes.

Keywords: Health promotion; Moderate to vigorous physical activity; Obesity; Pediatric; Sedentary activity; Sleep duration.

Publication types

Randomized Controlled Trial
Research Support, N.I.H., Extramural

MeSH terms

Adolescent
Exercise
Humans
Schools
Sedentary Behavior*
Sleep*
Time Factors

Abstract

Publication types

MeSH terms

Grants and funding