The Mediating Role of Negative Mood Affect in the Relationship Between Perceived Stress and Vulnerability to Insomnia Among Student Pharmacist Shift Workers

Mohammed F Salahuddin,1 Blesson I Samuel,2 Richard Bugingo,1 Delilah Spencer,1 Md Dilshad Manzar,3 Ahmed S BaHammam4,5 1Department of Pharmaceutical Sciences, School of Pharmacy & Health Professions, Notre Dame of Maryland University, MD, 21210, USA; 2Independent Researcher, Chennai, India; 3Department of Nursing, College of Applied Medical Sciences, Majmaah University, Majmaah, 11952, Saudi Arabia; 4University Sleep Disorders Center, Department of Medicine, College of Medicine, King Saud University, Riyadh, Saudi Arabia; 5National Plan for Science and Technology, College of Medicine, King Saud University, Riyadh, Saudi ArabiaCorrespondence: Mohammed F Salahuddin, Department of Pharmaceutical Sciences, School of Pharmacy, Notre Dame of Maryland University, MD, 21210, USA, Email [email protected]: Perceived stress and vulnerability to develop insomnia are closely linked, with negative mood affect playing a key role. Shift workers, particularly student pharmacists juggling academic demands and irregular work schedules, are at heightened risk for stress-related sleep disturbances. While previous studies have explored their direct relationships, limited evidence exists on the dual role of negative mood affect as both a mediator and a non-mediator in these pathways. This study investigates the mediating role of negative mood affect in the relationship between perceived stress and vulnerability to develop insomnia and assesses whether negative mood affect mediates the reverse relationship.Methods: A cross-sectional study was conducted on 86 student pharmacist shift workers at Notre Dame of Maryland University. Participants completed validated self-report measures, including the Perceived Stress Scale (PSS), the Ford Insomnia Response to Stress Test (FIRST), and the Positive and Negative Affect Schedule (PANAS). Mediation analysis using Hayes’ PROCESS macro (Model 4) examined the mediating role of negative mood affect in both pathways. Bias-corrected bootstrapping with 5000 iterations calculated confidence intervals for indirect effects, with significance set at p < 0.05.Results: Negative mood affect partially mediated the relationship between perceived stress and vulnerability to develop insomnia. Higher stress levels were associated with increased negative mood affect (b = 0.49, SE = 0.05, p < 0.01), which, in turn, was linked to greater insomnia vulnerability (b = 0.39, SE = 0.04, p < 0.01). The indirect effect was significant (b = 0.19, 95% CI [0.06, 0.33]). In contrast, negative mood affect did not mediate the reverse pathway (p = 0.15).Conclusion: Negative mood affect significantly mediates the relationship between perceived stress and insomnia vulnerability but not the reverse pathway. Interventions targeting emotional regulation may help reduce stress-related sleep disturbances. Longitudinal studies are needed to confirm these findings and refine interventions.Plain Language Summary: Student pharmacists who work irregular shifts often experience high levels of stress and disrupted sleep, which can negatively impact their health, academic performance, and overall well-being. This study explored how negative mood, including feelings of anxiety, irritability, and sadness, might explain the connection between perceived stress and vulnerability to insomnia.The findings revealed that higher stress levels were linked to increased negative mood, which in turn heightened vulnerability to insomnia. However, when examining the reverse pathway, whether insomnia influences stress through negative mood, the results showed no significant effect. This suggests that while negative mood plays a key role in how stress contributes to sleep problems, it does not explain how poor sleep might increase stress.These results highlight the importance of emotional regulation strategies, such as mindfulness or counseling, in managing stress and improving sleep health among student pharmacists. Addressing negative mood could break the cycle between stress and sleep disturbances. Future research should investigate these relationships over time and consider other factors, like coping mechanisms or cognitive arousal, to provide a more comprehensive understanding. Meanwhile, academic institutions and healthcare organizations can use these insights to create wellness programs that support both mental health and sleep quality for student pharmacists working demanding shifts. Keywords: sleep disturbances, emotional regulation, psychological stress, mood-sleep connection