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. 2025 Apr 11;48(4):zsaf031.
doi: 10.1093/sleep/zsaf031.

Circadian phase in high-school students: weekday-weekend shifts and relationships to other sleep/circadian characteristics

Brant P Hasler  1 , Nina Oryshkewych  1 , Meredith L Wallace  1 , Duncan B Clark  1 , Greg J Siegle  1 , Daniel L Buysse  1
Affiliations

Circadian phase in high-school students: weekday-weekend shifts and relationships to other sleep/circadian characteristics

Brant P Hasler et al. Sleep. .

Abstract

Study objectives: In a sample of high-school students, (1) to characterize within-person changes in sleep and circadian characteristics from school nights to weekend nights, (2) to examine whether later circadian phase relates to weekday-weekend changes in sleep/circadian characteristics, and (3) to examine correlations between biological and proxy measures of circadian phase.

Methods: Sample included 95 high-school students reporting at least one drink of alcohol in their lifetime. Participants completed baseline self-report measures, wrist actigraphy for 8 days, and two overnight laboratory visits (Thursday and Sunday) for salivary melatonin sample collection. Circadian phase was calculated as the dim light melatonin onset (DLMO; 4 pg/mL threshold). Proxy circadian phase measures included the Composite Scale of Morningness (CSM), Munich Chronotype Questionnaire (MCTQ), and actigraphy-based midsleep.

Results: Other than nap duration, all examined actigraphy-based sleep characteristics, DLMO, and DLMO-sleep phase angles showed weekday-weekend differences (adjusted p-value < .05). Later mean DLMO was associated with larger weekday-weekend changes in total sleep time (b = 0.39, padjusted = .010). CSM and actigraphy-based midsleep showed small-to-moderate (rho = ~0.3) and moderate (rho = ~0.5) correlations with DLMO, respectively, but chronotype based on the MCTQ was not correlated with DLMO.

Conclusions: In the largest published sample to date, circadian phase substantially shifted from the school week to weekend, underscoring the "social jetlag" imposed by early school start times. Similarly, teens with the latest circadian phase exhibited the greatest weekend catch-up sleep. Finally, perhaps due to the instability of circadian phase in this context, self-reported proxies for circadian timing were poor approximations of biological circadian phase.

Keywords: actigraphy; adolescents; chronotype; circadian misalignment; dim light melatonin onset; social jetlag.

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Conflict of interest statement

Financial disclosures: D.J.B. has served as a paid to Sleep Number over the past 3 years. He is an author of the Pittsburgh Sleep Quality Index, Pittsburgh Sleep Quality Index Addendum for PTSD (PSQI-A), Brief Pittsburgh Sleep Quality Index (B-PSQI), Daytime Insomnia Symptoms Scale, Pittsburgh Sleep Diary, Insomnia Symptom Questionnaire, and RU_SATED (copyright held by University of Pittsburgh). These instruments have been licensed to commercial entities for fees. He is also coauthor of the Consensus Sleep Diary (copyright held by Ryerson University), which is licensed to commercial entities for a fee. G.J.S. has a patent for vibroacoustic stimulation, licensed to Apollo Neuroscience, and for which he receives royalties. M.L.W. is a paid statistical consultant for Noctem Health and Health Rhythms. She also receives an honorarium as a Senior Associate Statistical Editor of Sleep Health.

Nonfinancial disclosures: None.

Figures

Graphical Abstract
Graphical Abstract
Figure 1.
Figure 1.
Study design (abbreviated for present project).
Figure 2.
Figure 2.
Later circadian phase associated with larger weekday–weekend differences in TST. Moderation was tested using linear mixed-effect models and an interaction between a continuous measure of mean DLMO-4 (averaged across Thursday and Sunday assessments) and day-of-week, accounting for age, assigned sex at birth, racial identity, and SES. Post-hoc contrasts were used to probe the interaction and compare participants with early (DLMO-1SD), middle (mean DLMO), and late (DLMO + 1SD) circadian phase.
Figure 3.
Figure 3.
Later circadian phase associated with later midsleep timing across weekdays and weekends. Moderation was tested using linear mixed-effect models and an interaction between a continuous measure of mean DLMO-4 (averaged across Thursday and Sunday assessments) and day-of-week, accounting for age, assigned sex at birth, racial identity, and SES. We then ran posthoc contrasts to probe the interaction and compare participants with early (DLMO-1SD), middle (mean DLMO), and late (DLMO + 1SD) circadian phase.
Figure 4.
Figure 4.
Earlier circadian phase associated with DLMO-sleep onset phase angles across weekdays and weekends. Moderation was tested using linear mixed-effect models and an interaction between a continuous measure of mean DLMO-4 (averaged across Thursday and Sunday assessments) and day-of-week, accounting for age, assigned sex at birth, racial identity, and SES. We then ran posthoc contrasts to probe the interaction and compare participants with early (DLMO-1SD), middle (mean DLMO), and late (DLMO + 1SD) circadian phase.
Figure 5.
Figure 5.
Later circadian phase associated with shorter DLMO-sleep offset phase angles across weekday and weekends. Moderation was tested using linear mixed-effect models and an interaction between a continuous measure of mean DLMO-4 (averaged across Thursday and Sunday assessments) and day-of-week, accounting for age, assigned sex at birth, racial identity, and SES. We then ran posthoc contrasts to probe the interaction and compare participants with early (DLMO-1SD), middle (mean DLMO), and late (DLMO + 1SD) circadian phase.
Figure 6.
Figure 6.
Bivariate Spearman correlations between objective circadian measures and proxy circadian measures (bold indicates adjusted p-value < .05). Correlations adjusted for covariates including age, assigned sex at birth, racial identity, and SES.
See this image and copyright information in PMC

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