Sleep and Skin Health: A Literature Review of Sleep Quality, Circadian Rhythms, and Cutaneous Physiology in Healthy Adults

This registration documents the methodological protocol of a completed literature review examining the relationship between sleep quality, circadian rhythms, and skin physiology in healthy adults (18–64 years). The review was conducted following PRISMA-ScR guidelines and organized evidence across four physiological domains: skin barrier function, visible skin changes, thermoregulation, and neuroendocrine/autonomic regulation. The objective was to systematically map available evidence on sleep-skin relationships in healthy adults, positioning sleep as a modifiable determinant of skin health in clinical dermatology. SEARCH STRATEGY Comprehensive searches were performed in: PubMed (MEDLINE), EMBASE, Scopus, Web of Science, Cochrane Central Register of Controlled Trials, LILACS (via BVS), SciELO, and ProQuest. Search period: April 2–12, 2025. No publication date restrictions were applied. Languages: English, Spanish, and Portuguese. Search terms: Sleep-related terms (sleep quality, sleep duration, sleep deprivation, circadian rhythm, chronotype) combined with dermatological outcomes (skin barrier function, transepidermal water loss, skin aging, cutaneous physiology). ELIGIBILITY CRITERIA Inclusion: Healthy adults (18–64 years) without chronic dermatological or sleep disorders, assessing sleep parameters and reporting quantifiable skin physiological outcomes, published in English, Spanish, or Portuguese. Exclusion: Diseased populations, pediatric and geriatric cohorts, and non-human research. SELECTION PROCESS Title and abstract screening was conducted independently by two reviewers using Rayyan (rayyan.ai). Discrepancies were resolved through consensus or third-reviewer adjudication. Inter-rater agreement: 76.5% observed agreement; Cohen's κ = 0.48 (moderate agreement, Landis & Koch criteria). After removal of 1,792 duplicates, 7,422 records were screened. A total of 118 full-text reports were assessed for eligibility. RESULTS 22 studies met predefined inclusion criteria and were included in the final synthesis. DATA EXTRACTION Data extraction was performed using a standardized form, independently verified by the authors. SYNTHESIS Findings were synthesized narratively and organized into four domains: (1) barrier function, (2) visible skin changes, (3) thermoregulation, and (4) neuroendocrine regulation. RETROSPECTIVE REGISTRATION NOTE Data extraction and synthesis were completed prior to this registration