Figure 1

![Figure 1: Prevalence of insomnia stratified by serum vitamin D status and tobacco smoke exposure categories in a cross-sectional analysis of US adults.](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10759233/bin/fnut-10-1285494-g0001.jpg)

> Source: Tianci Gao et al. "The roles of serum vitamin D and tobacco smoke exposure in insomnia: a cross-sec." *Frontiers in nutrition*, 2023. PMID: [38170097](https://pubmed.ncbi.nlm.nih.gov/38170097/)

<figure>
  <img src="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10759233/bin/fnut-10-1285494-g0001.jpg" alt="Prevalence of insomnia stratified by serum vitamin D status and tobacco smoke exposure categories in a cross-sectional analysis of US adults." />
  <figcaption>Figure 1. Prevalence of insomnia stratified by serum vitamin D status and tobacco smoke exposure categories in a cross-sectional analysis of US adults.<br>  Source: Tianci Gao et al. "The roles of serum vitamin D and tobacco smoke exposure in insomnia: a cross-sec." <em>Frontiers in nutrition</em>, 2023. PMID: <a href="https://pubmed.ncbi.nlm.nih.gov/38170097/">38170097</a></figcaption>
</figure>