The risk of alopecia areata and other related autoimmune diseases in patients with sleep disorders: a Korean population–based retrospective cohort study

The aim of our study was to investigate the risk of alopecia areata occurrence in patients with sleep disorders. This study was a retrospective cohort study based on the National Health Insurance Service-National Sample Cohort database of patients with a sleep disorder, along with age- and sex-matched control subjects from 2003 to 2013. The hazard ratio (HR) of alopecia areata was compared between the patients with sleep disorders and control subjects adjusting comorbid diseases which could affect the incidence of alopecia areata. We also compared the prevalence of comorbid diseases in the patients with sleep disorders and control subjects. Among the 25,800 patients with sleep disorders and the 129,000 control subjects, patients with sleep disorders were at a significantly increased risk for alopecia areata when compared with control subjects (adjusted HR 1.651 [95% CI 1.382-1.974]), especially in younger age groups (0-24 and 25-44 years). In a multivariate logistic analysis, sleep disorders were not only associated with alopecia areata (OR 1.913 [95% CI 1.717-2.171]), but also with other comorbid diseases, including solid-organ cancers (OR 1.099 [95% CI 1.049-1.151]), Graves' disease (OR 1.717 [95% CI 1.562-1.886]), Hashimoto thyroiditis (OR 1.641 [95% CI 1.413-1.905]), vitiligo (OR 1.539 [95% CI 1.236-1.917]), and rheumatoid arthritis (OR 1.886 [95% CI 1.780-1.998]). This study demonstrated that sleep disorder is an independent risk factor for alopecia areata, especially in individuals under the age of 45 years old.