KMAN Publication Inc. (KMANPUB) Psychology of Woman Journal 3041-8615 6 Serial Number 24 2025 10 01 Investigating the Mediating Role of Negative Repetitive Thoughts in the Relationship Between Behavioral Brain Systems and Sleep Quality With Mental Fatigue in Women With Type 2 Diabetes Investigating the Mediating Role of Negative Repetitive Thoughts in the Relationship Between Behavioral Brain Systems and Sleep Quality With Mental Fatigue in Women With Type 2 Diabetes 1 8 10.61838/kman.pwj.4288 EN Journal Article 2025 04 13 <p><strong>Objective:</strong> The present study aimed to determine the mediating role of negative repetitive thoughts in the relationship between behavioral brain systems and sleep quality with mental fatigue in women with type 2 diabetes.</p> <p><strong>Materials and Methods:</strong> This study was a correlational design using structural equation modeling. The statistical population included all women with type 2 diabetes who were members of the Diabetes Patients Support Association in Tehran Province in 2025. A total of 265 women were selected as the research sample through convenience sampling. The instruments used in this study included the Negative Repetitive Thoughts Questionnaire (McEvoy, Mahoney, &amp; Moulds, 2012), the Behavioral Inhibition/Activation Systems Scale (Carver &amp; White, 1994), the Pittsburgh Sleep Quality Index (Buysse et al., 1989), and the Mental Fatigue Questionnaire (Smets, 1996). The data were analyzed using path analysis.</p> <p><strong>Findings:</strong> The results showed that there was a significant and positive relationship between behavioral brain systems and sleep quality with mental fatigue through the mediation of negative repetitive thoughts. However, negative repetitive thoughts did not play a significant mediating role in the relationship between the behavioral activation system and mental fatigue.</p> <p><strong>Conclusion:</strong> Our findings suggest that negative repetitive thoughts, behavioral brain systems, and sleep quality can be considered fundamental constructs in chronic illnesses such as type 2 diabetes. It can be concluded that these mechanisms may play a critical role in the persistence of the disease, and considering these relationships could be beneficial for the etiology and treatment of individuals with type 2 diabetes.</p> https://journals.kmanpub.com/index.php/psywoman/article/download/4288/8769