Two-way association between alopecia areata and sleep disorders: A systematic review of observational studies

BACKGROUND: Alopecia Areata (AA) is found to be the most prevalent autoimmune disorder amongst the general population. It was observed that AA patients are at a significantly higher risk of developing obstructive sleep apnea and non-apneic insomnia than patients without AA. On the contrary, patients with identified sleep disorders were found to be more prone to developing AA as compared to the patients without sleep disorders. This study, therefore, validated the hypothesis of a bidirectional association between AA and sleep disorders. AIMS: In this systematic review, our primary aim is to assess the prevalence of sleep disorders in Alopecia Areata patients while also assessing the inverse relationship between the two disorders. METHODS: A literature search of MEDLINE, Google Scholar and Cochrane CENTRAL was performed from their inception to April 2022. Articles were selected for inclusion if they met the following eligibility criteria: (a) Studies enrolling patients having alopecia areata to assess the sleep quality. (b) Studies assessing the risks of alopecia areata in individuals with sleep disorder (c) Studies evaluating the bidirectional association between alopecia areata and sleep quality. Case reports, commentaries, and editorials were excluded. The outcomes of recruited studies were qualitatively synthesised and study findings are summarized in the results section and tabulated in summary tables. RESULTS: Our search on electronic databases yielded 1562 articles. After abstract screening and full text review, 5 cross sectional and 3 cohort studies are included in this systematic review. Cases with PSQI scores higher than 5 and 6 were found to be in greater numbers amongst the AA patient population when compared to the control population (p < 0.001). Moreover, studies showed that patients with sleep disorders were greatly predisposed to develop subsequent AA as compared to patients without sleep disorders (aHR 4.70; 95% CI 3.99–5.54) (P < 0.0001). CONCLUSION: The findings from our results display a significant bi-directional cause-effect relation between AA and sleep disorders. However, more large-scale observational studies on this subject are required to further validate our findings.