Effect of Night Shift Work on Cortisol Levels and Sleep Patterns Among Nurses at the University of Calabar Teaching Hospital

Night shift work disrupts circadian rhythms and has been associated with hormonal dysregulation and chronic sleep deficits in healthcare workers globally. This study evaluated the effect of night shift work on cortisol levels and sleep patterns among nurses at the University of Calabar Teaching Hospital, Cross River State, South South Nigeria. Sixty nurses were recruited, comprising 30 regularly assigned to night shifts and 30 assigned to day shifts. Salivary cortisol was collected at four time points across a 24-hour period using standardised collection kits. Sleep patterns were assessed using the Pittsburgh Sleep Quality Index. Sociodemographic variables and shift schedules were documented via structured questionnaire. Independent t-tests and repeated-measures analysis were employed. Results revealed that night shift nurses had significantly flattened cortisol diurnal curves, indicating disrupted hypothalamic-pituitary-adrenal axis function. Sleep quality scores were significantly worse among night shift workers, with shorter total sleep duration and frequent nocturnal awakening. Night shift nurses also reported higher fatigue and lower mood ratings. The study concludes that chronic night shift work imposes measurable neuroendocrine and sleep disruption burdens on nurses in Calabar. Rotating shift scheduling, fatigue management policies, and institutional wellness programmes are recommended to safeguard healthcare worker health. Keywords: night shift, cortisol, sleep quality, nurses, Calabar.