A comparison of sleep-wake patterns among school-age children and adolescents in Hong Kong before and during the COVID-19 pandemic

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Lifestyle of children and adolescents have changed extensively during the COVID-19 pandemic due to school suspension and social distancing measures, which can affect their sleep health. Existing studies in the area used convenient samples and focused on the initial months of the pandemic.


As part of a territory-wide epidemiological study in Hong Kong, this cross-sectional study recruited primary and secondary school students by stratified random sampling. We investigated the pandemic’s effects on sleep parameters using multivariate regression, adjusting for age, sex, household income, seasonality and presence of mental disorders, and the effects’ moderators and mediators.


Between September 1, 2019 and June 2, 2021, 791 primary and 442 school students were recruited and analysed. After correcting for multiple testing, being assessed during COVID predicted a longer sleep latency in primary and secondary school students in school days (95% CI = 1.0–5.2 minutes, adjusted p-value = 0.010; and 95% CI= 3.9–13.0 minutes, adjusted p-value =0.004, respectively) and non-school days (95% CI = 1.7–7.2 minutes, adjusted p-value = 0.005; 95% CI = 3.4–13.7 minutes, adjusted p-value = 0.014, respectively). Low household income was a moderator for later bedtime (adjusted p-value = 0.032) and later sleep onset (adjusted p-value = 0.043) during non-school days among secondary school students. Sex and digital leisure time were not moderator and mediator of the pandemic’s effect on sleep parameters, respectively.


Changes associated with the COVID-19 pandemic have a widespread and enduring effect on sleep health of school-aged students in Hong Kong. Household income play a role in adolescents’ sleep health’s resilience against these changes, and anti-epidemic measures effects on the health gap of the youth should be considered.


Government of the Hong Kong Special Administrative Region, Food and Health Bureau, Health and Medical Research Fund (Ref. No.: MHS-P1(Part 1)-CUHK).

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  1. SciScore for 10.1101/2022.06.01.22275778: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    EthicsConsent: Written parental consent was obtained from all student participants.
    IRB: The study was approved by the Joint Chinese University of Hong Kong – New Territories East Cluster Clinical Research Ethics Committee (Ref. no: 2018.497).
    Sex as a biological variablenot detected.
    RandomizationThe study adopted a two-stage random sampling method.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    No key resources detected.

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    Strengths and Limitations: The key strength of this study is the use of a territory-wide, random sampling method. Together with a high response rate, we have captured a representative sample of school-aged children and adolescents in Hong Kong. Furthermore, we kept our sampling methodology consistent before and during COVID, making our data from the two periods comparable. The study has several limitations: First, this study was cross-sectional by nature and not longitudinal. Second, the sleep parameters were derived only from self-report or parent-report, without objective measures such as actigraphy. Third, our data did not capture daytime activities, limiting our interpretation of mediating factors of changes.

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    Results from scite Reference Check: We found no unreliable references.

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