Introduction: The Endicott Work Productivity Scale (EWPS) is a self-report assessment of occupational functioning. We correlated global and subscale EWPS scores to evoked response potentials (ERPs), objective measures of cognitive function, in a sample of shift workers. Methods: 34 night workers participated in an overnight neurophysiology (e.g., ERP) assessment. Subjects with a history of insomnia or other sleep disorders prior to shift work were excluded. At 17:00, each subject completed an Endicott Work Productivity Scale (EWPS). At 18:00, each participant performed an "active" attention ERP task. Mean electrical amplitudes corresponding to attentional orienting (P3a) and target detection (P3b) were calculated and compared across all participants. Results: Total EWPS scores were correlated with the P3a, an attention-to-novelty response (Cpz, r = -.344, p < .05). The fatigue subscale (items such as losing interest, becoming reckless, and falling asleep at work) was correlated to the P3a response (Cpz, r = -.523; Pz, r = -.511, p < .01), as was the executive function subscale (difficulty concentrating, organizing work, and forgetting information: CZp, r = -.343, p < .05). Three subscales measuring interpersonal interactions, work efficiency, and counterproductive work behavior did not significantly relate to ERP amplitudes. None of the EWPS scores related to P3b (target detection) amplitudes. Conclusion: ERP measures of attentional orienting were related to several components of self-reported occupational performance in a sample of night shift workers. Specifically, the P3a, a measure of frontal attention orienting, was highly sensitive to scale items assessing executive function. We found no evidence for a relationship between work functions and the parietal P3b response associated with target detection and memory update processes, supporting the notion that impairments seen in Shift Work Disorder are largely distributed over the frontal lobe.
V. Gumenyuk, Sleep Disorders and Research Center, Henry Ford Hospital, Detroit, MI, USA