Table 3.
Association between vitamin D and sleep quality during the COVID-19 pandemic
| Total |
Exposure to sunlight † |
||||||||
|---|---|---|---|---|---|---|---|---|---|
| Unadjusted |
Adjusted * |
Sufficient (64.9%) |
Insufficient (35.1%) |
||||||
| OR | 95% CI | OR | 95% CI | OR | 95% CI | OR | 95% CI | ||
| Vitamin D | |||||||||
| Sufficiency | 1.00 | 1.00 | 1.00 | 1.00 | |||||
| Deficiency | 1.17 | 0.68–2.02 | 1.08 | 0.63–1.82 | 0.85 | 0.43–1.72 | 2.02 | 1.10–3.71 | |
| AIC | 2362.622 | 2280.924 | 1261.312 | 949.934 | |||||
| Continuous value | |||||||||
| ng/mL | 0.99 | 0.98–1.01 | 1.00 | 0.98–1.03 | 1.02 | 0.99–1.06 | 0.96 | 0.92–0.99 | |
| AIC | 2359.420 | 2190.415 | 1257.890 | 950.658 | |||||
AIC, Akaike information criterion.
The outcome variable evaluated was poor sleep quality (Pittsburgh Sleep Quality Index ≥5); vitamin D concentrations were classified according to the Institute of Medicine as deficient when 25(OH)D < 20 ng/mL and sufficient when 25(OH)D ≥ 20 ng/mL
Directed acyclic graph (DAG) was used to support the theoretical model for the adjusted analysis. Adjusted analysis was by the following minimum and sufficient set of variables: age (continuous variable), sex (male or female), skin color (white, black, brown, or other), education (0 to 8 y, 9 to 11 y, or >12 y), employment status (not working or actively working), alcohol consumption (no or yes), body mass index (continuous variable; kg/m2), presence of chronic diseases (no or yes), mental health (presence of anxiety or depression symptoms), physical activity (physically active or physically inactive), exposure to sunlight (continuous variable, min/d), and vitamin D supplementation (no or yes).
Analysis stratified by solar exposure and the minimum and sufficient set of variables is presented.