• Luiz Antônio Alves de Menezes-Júnior, Thais da Silva Sabião, Samara Silva de Moura, Aline Priscila Batista, Mariana Carvalho de Menezes, Júlia Cristina Cardoso Carraro, AndradeAmanda Cristina de SouzaACSDepartment of Public Health, Federal University of Mato Grosso, Cuiabá, Mato Grosso, Brazil. Electronic address: csouza.amanda@gmail.com., George Luiz Lins Machado-Coelho, and Adriana Lúcia Meireles.
• Postgraduate Program in Health and Nutrition, School of Nutrition, Federal University of Ouro Preto, Ouro Preto, Minas Gerais, Brazil; Research and Study Group on Nutrition and Public Health (GPENSC), Federal University of Ouro Preto, Brazil. Electronic address: luiz.menezes@ufop.edu.br.
• Nutrition. 2023 Jun 1; 110: 112008112008.

ObjectivesThis study aimed to evaluate the association of vitamin D with sleep quality during the COVID-19 pandemic and the influence of daily sunlight on this association.MethodsThis cross-sectional, population-based study among adults stratified by multistage probability cluster sampling was conducted from October to December 2020 in the Iron Quadrangle region of Brazil. The outcome was sleep quality, evaluated by the Pittsburgh Sleep Quality Index. Vitamin D (25-hydroxyvitamin D) concentrations were determined by indirect electrochemiluminescence and a deficiency was classified as 25(OH)D < 20 ng/mL. To assess sunlight, the average daily sunlight exposure was calculated and was classified as insufficient when less than 30 min/d. Multivariate logistic analysis was used to estimate the association between vitamin D and sleep quality. A directed acyclic graph was used to select minimal and sufficient sets of adjustment variables for confounding from the backdoor criterion.ResultsIn a total of 1709 individuals evaluated, the prevalence of vitamin D deficiency was 19.8% (95% CI, 15.5-24.9%), and the prevalence of poor sleep quality was 52.5% (95% CI, 48.6-56.4%). In multivariate analysis, vitamin D was not associated with poor sleep quality in individuals with sufficient sunlight. Moreover, in individuals with insufficient sunlight, vitamin D deficiency was associated with poor sleep quality (odds ratio [OR], 2.02; 95% CI, 1.10-3.71). Furthermore, each 1-ng/mL increase in vitamin D levels reduced the chance of poor sleep quality by 4.2% (OR, 0.96; 95% CI, 0.92-0.99).ConclusionsVitamin D deficiency was associated with poor sleep quality in individuals with insufficient exposure to sunlight.Copyright © 2023 Elsevier Inc. All rights reserved.

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