INTRODUCTION: Cardiorespiratory fitness (CRF) is a vital sign that can improve risk classification for adverse health outcomes. While lifestyle-related factors are associated with CRF, few have examined the influence of sleep characteristics, especially in youths. Social jetlag, a mismatch between one's biological clock and sleep schedule, is prevalent in adolescents and associated with increased adiposity, though its relationship with CRF is unclear.
OBJECTIVE: To quantify the relationship between social jetlag and CRF, independent of other sleep characteristics.
METHODS: This cross-sectional sample includes 276 New Zealand adolescents (14-18 years, 52.5% female). CRF (VO2max) was estimated from a 20-m multi-stage shuttle run. Average sleep duration, sleep disturbances, social jetlag, physical activity, and the number of bedroom screens were estimated from validated self-report surveys. Social jetlag is the difference in hours between the midpoint of sleep during weekdays (school) and weekend days (free). Combined and sex-stratified linear regression assessed the association between sleep outcomes and CRF, controlling for relevant covariates.
RESULTS: Males slept 17.6 min less, had less sleep disturbances, and a 25.1-min greater social jetlag than their female peers (all p
* Title and MeSH Headings from MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.