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. 2022 May 10;12(5):e055716.
doi: 10.1136/bmjopen-2021-055716.

The CLASS Study (Circadian Light in Adolescence, Sleep and School): protocol for a prospective, longitudinal cohort to assess sleep, light, circadian timing and academic performance in adolescence

Julia E Stone  1 , Joshua Wiley  2 , Evangelos Chachos  2 , Anthony J Hand  2 , Sinh Lu  2 , Monika Raniti  2   3   4 , Elizabeth Klerman  5   6   7 , Steven W Lockley  6   7 , Mary A Carskadon  8 , Andrew J K Phillips  2 , Bei Bei #  2 , Shantha M W Rajaratnam #  2   6   7 ; CLASS Study Team
Affiliations

The CLASS Study (Circadian Light in Adolescence, Sleep and School): protocol for a prospective, longitudinal cohort to assess sleep, light, circadian timing and academic performance in adolescence

Julia E Stone et al. BMJ Open. .

Abstract

Background: During adolescence, sleep and circadian timing shift later, contributing to restricted sleep duration and irregular sleep-wake patterns. The association of these developmental changes in sleep and circadian timing with cognitive functioning, and consequently academic outcomes, has not been examined prospectively. The role of ambient light exposure in these developmental changes is also not well understood. Here, we describe the protocol for the Circadian Light in Adolescence, Sleep and School (CLASS) Study that will use a longitudinal design to examine the associations of sleep-wake timing, circadian timing and light exposure with academic performance and sleepiness during a critical stage of development. We also describe protocol adaptations to enable remote data collection when required during the COVID-19 pandemic.

Methods: Approximately 220 healthy adolescents aged 12-13 years (school Year 7) will be recruited from the general community in Melbourne, Australia. Participants will be monitored at five 6 monthly time points over 2 years. Sleep and light exposure will be assessed for 2 weeks during the school term, every 6 months, along with self-report questionnaires of daytime sleepiness. Circadian phase will be measured via dim light melatonin onset once each year. Academic performance will be measured via national standardised testing (National Assessment Program-Literacy and Numeracy) and the Wechsler Individual Achievement Test-Australian and New Zealand Standardised Third Edition in school Years 7 and 9. Secondary outcomes, including symptoms of depression, anxiety and sleep disorders, will be measured via questionnaires.

Discussion: The CLASS Study will enable a comprehensive longitudinal assessment of changes in sleep-wake timing, circadian phase, light exposure and academic performance across a key developmental stage in adolescence. Findings may inform policies and intervention strategies for secondary school-aged adolescents.

Ethics and dissemination: Ethical approval was obtained by the Monash University Human Research Ethics Committee and the Victorian Department of Education. Dissemination plans include scientific publications, scientific conferences, via stakeholders including schools and media.

Study dates: Recruitment occurred between October 2019 and September 2021, data collection from 2019 to 2023.

Keywords: COVID-19; Child & adolescent psychiatry; MENTAL HEALTH; SLEEP MEDICINE.

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Conflict of interest statement

Competing interests: JES, MR, EC, AJH, SL, JW, MAC and BB have no conflicts to declare. AJKP was an investigator on projects supported by the CRC for Alertness, Safety and Productivity, and he has received research funding from Versalux and Delos. EBK reports (non-government, non-university): Travel support from World Conference of Chronobiology, Gordon Research Conference, Sleep Research Society, Santa Fe Institute, German Sleep Society (DGSM); Consulting/grant reviews income from Puerto Rice Science, Technology, and Research Trust, National Sleep Foundation, Sanofi-Genzyme; Family member owns Chronsulting. SWL has had a number of commercial interests in the last 2 years (2019–2021). His interests were reviewed and managed by Mass General Brigham in accordance with their conflict of interest policies. No interests are directly related to the research or topic reported in this paper but, in the interests of full disclosure, are outlined below. SWL has received consulting fees from the EyeJust, Rec Room, Six Senses, and Stantec; and has current consulting contracts with Akili Interactive; Apex 2100; Consumer Sleep Solutions; Hintsa Performance AG; KBR Wyle Services, Light Cognitive; Lighting Science Group Corporation/HealthE; Look Optic; Mental Workout/Timeshifter and View. He has received honoraria and travel or accommodation expenses from MIT, Roxbury Latin School, and University of Toronto, and travel or accommodation expenses (no honoraria) from Wiley; and royalties from Oxford University Press. He holds equity in iSleep Pty. He has received an unrestricted equipment gift from F. Lux Software LLC, and holds an investigator-initiated grant from F. Lux Software. He has a Clinical Research Support Agreement and a Clinical Trials Agreement with Vanda Pharmaceuticals. He is an unpaid Board Member of the Midwest Lighting Institute (non-profit). He was a Program Leader for the CRC for Alertness, Safety and Productivity, Australia, through an adjunct professor position at Monash University (2015–2019). He is currently a part-time faculty member at the University of Surrey. He has served as a paid expert in legal proceedings related to light, sleep and health. SMWR was a Program Leader for the CRC for Alertness, Safety and Productivity, Australia, and currently serves as the Chair of the Sleep Health Foundation. SMWR reports grants from Vanda Pharmaceuticals, Philips Respironics, Cephalon, Rio Tinto and Shell and receiving equipment support and consultancy fees through his institution from Vanda, Circadian Therapeutics, Optalert, Tyco Healthcare, Compumedics, Mental Health Professionals Network and Teva Pharmaceuticals, which are not related to this paper.

Figures

Figure 1
Figure 1
Protocol flow chart for the Circadian Light in Adolescence, Sleep and School (CLASS) Study. Data are collected in five waves, each approximately 6 months apart, starting when the participant is in Year 7 (age 12–13 years). Academic assessments and sleep interviews occur within ±2 weeks of the Dim Light Melatonin Onset (DLMO) assessment.
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