Associations Between Asthma Control, Insomnia Severity, and Psychosocial Outcomes: A Cross-Sectional Mediation Analysis

Background/Objectives: Insomnia is highly prevalent among patients with asthma and has been associated with systemic inflammation, reduced lung function, and increased mortality. This study investigated whether insomnia mediates the relationship between asthma control and psychosocial dysfunction, including social anhedonia and functional impairment. Methods: This cross-sectional study included 153 adults with physician-diagnosed asthma classified as controlled (n = 51) or uncontrolled (n = 102) according to the Asthma Control Test (ACT). Insomnia severity was assessed using the Athens Insomnia Scale (AIS), social anhedonia using the Revised Social Anhedonia Scale (RSAS), psychological distress using DASS-21, and functional impairment using the Functioning Assessment Short Test (FAST). Results: Uncontrolled asthma was associated with significantly higher insomnia severity and greater depression, anxiety, and stress levels (all p < 0.001). Asthma control emerged as the strongest independent predictor of insomnia severity (β = −0.451, p < 0.001). Although asthma control was not directly associated with social anhedonia or functional impairment, insomnia significantly mediated these relationships. The indirect effect of asthma control on social anhedonia via insomnia was significant (B = −0.1162, 95% CI −0.2384, −0.0029), as was the indirect effect on functional impairment (B = −0.4953, 95% CI −0.8656, −0.1038). Spirometric indices were not independently associated with psychosocial outcomes. Conclusions: Insomnia may represent an important intermediary process linking poor asthma control to psychosocial dysfunction. These findings highlight the clinical importance of assessing sleep disturbances in asthma patients and suggest that insomnia may contribute to broader psychosocial impairment beyond respiratory symptoms alone.