Influence of sunlight on the association between 25-hydroxyvitamin D levels and sleep quality in Brazilian adults: A population-based study

• Published in: Nutrition (Burbank, Los Angeles County, Calif.) Vol. 110; p. 112008
• Main Authors: de Menezes-Júnior, Luiz Antônio Alves, Sabião, Thais da Silva, de Moura, Samara Silva, Batista, Aline Priscila, de Menezes, Mariana Carvalho, Carraro, Júlia Cristina Cardoso, Andrade, Amanda Cristina de Souza, Machado-Coelho, George Luiz Lins, Meireles, Adriana Lúcia
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01-06-2023; Elsevier Limited
• Subjects: 25-Hydroxyvitamin D; Adult; Adults; Brazil - epidemiology; Calcifediol; Calciferol; Circadian rhythm; Coronaviruses; COVID-19; COVID-19 - complications; Cross-Sectional Studies; Electrochemiluminescence; Epidemiology; Evaluation; Households; Humans; Multivariate analysis; Nutrient deficiency; Pandemics; Pittsburgh Sleep Quality Index; Population studies; Population-based studies; Sleep; Sleep Quality; Sunlight; Vitamin D; Vitamin D Deficiency - complications; Vitamin D Deficiency - epidemiology; Vitamins; Brazil; Pittsburgh Sleep Quality Index; Sunlight; Circadian rhythm; Calciferol
• ISSN: 0899-9007; 1873-1244; 1873-1244
• DOI: 10.1016/j.nut.2023.112008

•Three in 10 Brazilian adults assessed had vitamin D deficiency during the COVID-19 pandemic.•Vitamin D was associated with sleep quality only in adults with insufficient exposure to sunlight.•The association of vitamin D deficiency with sleep quality was influenced by sunlight.
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This 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.
This 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.
In 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).
Vitamin D deficiency was associated with poor sleep quality in individuals with insufficient exposure to sunlight.