{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,15]],"date-time":"2026-04-15T09:44:52Z","timestamp":1776246292907,"version":"3.50.1"},"reference-count":30,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2026,4,15]],"date-time":"2026-04-15T00:00:00Z","timestamp":1776211200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100004901","name":"Minas Gerais Research Foundation","doi-asserted-by":"publisher","award":["APQ-04870-24"],"award-info":[{"award-number":["APQ-04870-24"]}],"id":[{"id":"10.13039\/501100004901","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Clocks &amp; Sleep"],"abstract":"<jats:p>Light exposure is a primary zeitgeber for the human circadian system and plays a key role in shaping sleep\u2013wake patterns during adolescence, a period marked by biological sensitivity and social constraints. How the temporal organization and spectral composition of daily light exposure differ between weekdays and weekends remains poorly understood. Eighteen adolescents (15\u201317 years) were monitored for seven days using wrist actigraphy with integrated light sensors. Sleep parameters, nonparametric circadian rhythm indices, and time-resolved profiles of ambient and spectral (blue, green, and red) light exposure were analyzed. Repeated-measures ANOVA tested the effects of time of day and day type. Total sleep time and time in bed were longer on weekdays than on weekends (p &lt; 0.05), while sleep latency and WASO did not differ. Circadian indices indicated preserved rhythmic organization. Light exposure showed a robust diurnal profile, with higher spectral irradiance on weekends (p &lt; 0.001), especially in the morning and early afternoon. Significant time \u00d7 day-type interactions were observed across all spectral bands (p &lt; 0.001), indicating systematic reshaping of daily light profiles. Adolescents exhibit weekday\u2013weekend differences in the temporal and spectral organization of light exposure, affecting the amplitude and shape of overall daily profiles.<\/jats:p>","DOI":"10.3390\/clockssleep8020019","type":"journal-article","created":{"date-parts":[[2026,4,15]],"date-time":"2026-04-15T08:11:18Z","timestamp":1776240678000},"page":"19","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Light Exposure Rhythms and Sleep Organization in Adolescents: Temporal Differences Between Weekdays and Weekends in an Actigraphic Study"],"prefix":"10.3390","volume":"8","author":[{"given":"Emilly Francianne Lamego da","family":"Silva","sequence":"first","affiliation":[{"name":"Laboratory of Neuroscience, Chronobiology, and Sleep Psychology, Room 101, State University of Minas Gerais, Divinopolis 35501-170, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0009-5504-2754","authenticated-orcid":false,"given":"Guilherme","family":"Martins","sequence":"additional","affiliation":[{"name":"Laboratory of Neuroscience, Chronobiology, and Sleep Psychology, Room 101, State University of Minas Gerais, Divinopolis 35501-170, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Francimara Diniz","family":"Ribeiro","sequence":"additional","affiliation":[{"name":"Laboratory of Neuroscience, Chronobiology, and Sleep Psychology, Room 101, State University of Minas Gerais, Divinopolis 35501-170, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Leonardo Martins Guimaraes","family":"Rossi","sequence":"additional","affiliation":[{"name":"Laboratory of Neuroscience, Chronobiology, and Sleep Psychology, Room 101, State University of Minas Gerais, Divinopolis 35501-170, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Milena Fernandes de","family":"Oliveira","sequence":"additional","affiliation":[{"name":"Laboratory of Neuroscience, Chronobiology, and Sleep Psychology, Room 101, State University of Minas Gerais, Divinopolis 35501-170, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3330-8007","authenticated-orcid":false,"given":"Camila Fernanda Cunha","family":"Brand\u00e3o","sequence":"additional","affiliation":[{"name":"Laboratory for Research in Metabolism, Physiology, Physical Exercise, State University of Minas Gerais, Divin\u00f3polis 35501-170, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6042-7757","authenticated-orcid":false,"given":"Lucas Rios","family":"Drummond","sequence":"additional","affiliation":[{"name":"Study and Research Group on Strength Training in Health, Physical Conditioning, State University of Minas Gerais, Divin\u00f3polis 35501-170, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lucas Tulio","family":"Lacerda","sequence":"additional","affiliation":[{"name":"Research Group on Exercise, Sports Physiology, State University of Minas Gerais, Divin\u00f3polis 35501-170, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Thais de Fatima Bittencourt","family":"Oliveira","sequence":"additional","affiliation":[{"name":"Laboratory of Neuroscience, Chronobiology, and Sleep Psychology, Room 101, State University of Minas Gerais, Divinopolis 35501-170, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2650-451X","authenticated-orcid":false,"given":"Michael Jackson Oliveira de","family":"Andrade","sequence":"additional","affiliation":[{"name":"Laboratory of Neuroscience, Chronobiology, and Sleep Psychology, Room 101, State University of Minas Gerais, Divinopolis 35501-170, Brazil"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,15]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1547","DOI":"10.1152\/physrev.00013.2010","article-title":"Intrinsically photosensitive retinal ganglion cells","volume":"90","author":"Do","year":"2010","journal-title":"Physiol. 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