Short Sleep Duration and Extremely Delayed Chronotypes in Uruguayan Youth: The Role of School Start Times and Social Constraints
Open accessAbstract
During adolescence, biological, psychosocial, and contextual factors converge in a “perfect storm” and have been put forward to explain the delay in chronotype observed at this age and the prevalence of disrupted sleep. This study provides evidence to support that chronotype and sleep patterns (particularly sleep duration) are socially constrained and to identify novel significant social predictors. Uruguayan public school activities are arranged in up to 4 shifts, creating a natural experiment to examine the effect of school timing on questionnaire-based assessments of sleep and chronotype. In this study, 268 high school students (15-18 years old) who attended school either on morning (0730 to 1130 h) or afternoon shifts (1130 h to 1530 h) responded to an adapted School Sleep Habits Survey. Students attending afternoon shifts had later chronotypes (a 1.5-h later midpoint of sleep on free days adjusted for sleep debt) than those attending the morning shift. Besides shift, evening social activities (including dinner time) were further identified as key predictors of late chronotypes, whereas age and gender were not. Sleep on school days was overall advanced and reduced with respect to weekends, and these effects were stronger in morning-shift students. Weekend sleep duration was similar between shifts, which probably caused the prevalence of reduced sleep durations (average weekly sleep duration, SDweek <8 h) to be higher in morning-shift students (almost 80%) than in afternoon-shift ones (34%). Reduced sleep duration was significantly higher in morning-shift students. In addition, age, chronotype, and dinner time became relevant determinants of sleep deficit only in the morning-shift students. Besides the important social constraint of early school start time, this is the first study to confirm the significance of other types of social pressures on both adolescents’ chronotype and sleep deficit, which can be useful as potential new targets for effective policies to protect adolescent sleep.
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Limited evidence suggests that adolescents with delayed chronotypes may be more adversely impacted by early school start times than other adolescents.
“In fact, limited evidence suggests that adolescents with delayed chronotypes may be even more adversely impacted by early school start times [121].”
From Later School Start Times as a Public Health Intervention to Promote Sleep Health in Adolescents (2023) · cites this paper as [121]
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Later School Start Times as a Public Health Intervention to Promote Sleep Health in Adolescents
Mousavi, Z., & Troxel, W. M. (2023) · Current Sleep Medicine Reports · doi:10.1007/s40675-023-00263-8 · Cited by 18 · see citing works
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A 4-year longitudinal study investigating the relationship between flexible school starts and grades
Biller, A. M., Molenda, C., Obster, F., Zerbini, G., Förtsch, C., Roenneberg, T., & Winnebeck, E. C. (2022) · Scientific Reports · doi:10.1038/s41598-022-06804-5 · Cited by 10 · see citing works
- Authors
- Estevan, I., Silva, A., Vetter, C., & Tassino, B.
- Affiliations
- Universidad de la República de Uruguay (UY)
- University of Colorado Boulder (US)
- Corresponding author
- Tassino, Bettina
- Venue
- Journal of Biological Rhythms
- Publisher
- SAGE Publications
- Published
- 2020-06-01
- Volume
- 35
- Issue
- 4
- Pages
- 391-404
- ISSN
- 0748-7304 (ISSN-L)
- 1552-4531
- OpenAlex
- W3030460744
- Cited by
- 51
- References
- 22
- Citations by year
- 2026: 8 · 2025: 3 · 2024: 4 · 2023: 11 · 2022: 5 · 2021: 3 · 2020: 17
- FWCI
- 8.70
- Type
- journal article
- Language
- en
- Open access
- green
- hdl.handle.net
- Licence
- Locations
- Journal of Biological Rhythms (publishedVersion)
- PubMed (publishedVersion)
- LA Referencia (Red Federada de Repositorios Institucionales de Publicaciones Científicas) (submittedVersion, cc-by-nc-nd)
- Funders
- agencia nacional de investigación e innovación (POS_NAC_2015_1_109643)
- universidad de la república uruguay (Iniciación 2017 #361)
- Topics
- Social Sciences › Psychology › Experimental and Cognitive Psychology › Sleep and related disorders
- Life Sciences › Neuroscience › Endocrine and Autonomic Systems › Circadian rhythm and melatonin
- Social Sciences › Psychology › Experimental and Cognitive Psychology › Sleep and Work-Related Fatigue
- Keywords
- adolescent sleep, chronotype, sleep duration, school start time, school shift, insufficient sleep
- MeSH terms
- Social Factors, Adolescent, Circadian Rhythm, Female, Humans, Male, Surveys and Questionnaires, Schools, Sleep, Sleep Deprivation, Students, Time Factors, Uruguay
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