Individual and Occupational Predictors of Sleep Intervention Response Among Shift-Working Firefighters

BackgroundCognitive Behavioral Therapy for Insomnia (CBT-I) is the first-line treatment for chronic insomnia, yet its effectiveness varies substantially across individuals. This variability is particularly pronounced in shift workers, who often experience irregular sleep-wake cycles and high levels of stress. ObjectiveWe examined heterogeneous CBT-I response patterns and their predictors in a high-risk shift-working firefighter cohort, with the goal of identifying modifiable clinical and occupational factors that can inform personalized intervention strategies. MethodsOver a five-week CBT-I intervention, self-reported sleep quality was longitudinally assessed in 50 participants (mean age = 34.8 {+/-} 7.7 years; 88% male). Growth mixture modeling identified latent response trajectories, and multinomial logistic regression examined predictors including sleep parameters, insomnia severity, alcohol use, and work-related characteristics. A validated mathematical alertness model was used to objectively characterize physiological response patterns. ResultsThree response patterns emerged: steady-poor (24%), steady-moderate (50%), and improving (26%). Poor response was associated with emergency duty, longer sleep onset latency, and higher insomnia severity. Improved response was predicted by 3-day shift cycles, lower alcohol intake, and shorter shift-work duration. Mathematical model-predicted alertness profiles paralleled subjective response trajectories. ConclusionsCBT-I response among shift workers is highly heterogeneous and shaped by both clinical and occupational factors. Identifying these moderators can guide tailored behavioral interventions to improve treatment outcomes for individuals with insomnia in demanding work environments.