Physiological Basis of Fatigue and Its Impact on Clinical Decision-Making Among Resident Doctors in Teaching Hospitals in Edo State, South South Nigeria

Background: Resident doctors in Nigerian teaching hospitals frequently work extended call shifts of 24 to 36 hours under conditions of chronic sleep restriction and high cognitive demand. Physiological fatigue arising from sleep deprivation adversely affects reaction time, working memory, and clinical decision quality, with patient safety implications. Systematic physiological characterisation of fatigue in Nigerian resident doctors is absent from the empirical literature. Objectives: This study aims to assess physiological fatigue markers, including salivary cortisol, psychomotor vigilance task performance, subjective sleepiness, and working memory scores, in resident doctors before and after 24-hour on-call duties at the University of Benin Teaching Hospital and Irrua Specialist Teaching Hospital. Methods: Forty residents across internal medicine, surgery, and obstetrics will be assessed at baseline (pre-call), immediately post-call, and after 8 hours of recovery sleep. A paired crossover design will be employed. Cortisol, psychomotor vigilance task, the Karolinska Sleepiness Scale, and N-back working memory tests will be administered at each time point. Repeated measures ANOVA and post-hoc Bonferroni tests will be applied. Expected Outcomes: Post-call assessments are expected to reveal significantly elevated cortisol, prolonged reaction times, higher sleepiness scores, and reduced working memory capacity compared to pre-call values. Conclusion: Findings will contribute physiological evidence to support duty hour reform advocacy in Nigerian postgraduate medical training. Keywords: physician fatigue, sleep deprivation, psychomotor vigilance, cortisol, resident doctors.