Physiological Effects of Night-Shift Work on Blood Pressure and Heart Rate Variability Among Nurses at the University of Calabar Teaching Hospital, South South Nigeria

Background: Shift work, particularly night-shift schedules, disrupts circadian rhythms and has been associated with adverse cardiovascular outcomes. Nigerian healthcare workers, including nurses, frequently engage in rotating and night shifts under conditions of staff shortages and extended working hours. The physiological consequences for nursing staff in South South Nigeria are inadequately documented. Objectives: This study seeks to compare resting blood pressure and heart rate variability between day-shift and night-shift nurses at the University of Calabar Teaching Hospital, and to assess whether shift type is an independent predictor of cardiovascular strain. Methods: Thirty night-shift and thirty day-shift nurses will be recruited. Blood pressure will be measured at the beginning and end of each shift. Short-term heart rate variability will be assessed using a validated portable device. Questionnaires will capture sleep hours, caffeine intake, and years of shift work experience. Paired and independent t-tests will be employed. Expected Outcomes: Night-shift nurses are hypothesised to exhibit significantly higher blood pressure readings and reduced heart rate variability indices, indicating greater autonomic cardiovascular stress. Conclusion: Findings will support evidence-based scheduling policy recommendations in Nigerian hospital administration. Keywords: night-shift work, blood pressure, heart rate variability, nurses, Calabar.