Possible Association between Toxoplasma gondii Infection and Sleep Disorders: A Systematic Review

Background: Few studies investigated the relationship between toxoplasmosis and sleep disorders. Sleep disorders can lead to suicidal behavior and traffic accidents. Therefore, the purpose of this study is to collect information and investigate the possible relationship between Toxoplasma gondii (T. gondii) and sleep disorders. Methods: To achieve the goal of the present study, five English databases (PubMed, ScienceDirect, Web of Science, Scopus, and ProQuest) were systematically searched for related studies from their inception until October 18, 2022. The obtained articles were screened based on the title, abstract, and full text. Then, the quality of the papers investigating the relationship between toxoplasmosis and sleep disorders was evaluated, and finally, the data from the relevant studies were extracted in a Microsoft Excel data sheet. Results: Eight articles (4 case-control and 4 cross-sectional studies) were entered in this systematic review containing 926 patients with sleep disorders and 1877 people without sleep disorders in casecontrol studies, out of which 212 (22.89%) and 392 (20.88%) individuals were positive for anti-T. gondii IgG antibody using different serological methods. Also, 2885 people with sleep disorders were investigated for anti-T. gondii IgG antibody in cross-sectional studies, out of which 1559 (54.03%) cases were positive. Conclusion: The results of this study suggest that T. gondii infection may be a risk factor for sleep disorders. However, the number of related studies is small, and there are contradictions in the findings of these articles. Therefore, further studies are necessary to clarify the possible association between T. gondii infections and sleep disorders.