Effects of Shift Work Type on Sleep Quality and Cortisol Regulation Among Nurses: A Prospective Observational Study.

May 27, 2026International journal of environmental research and public health

How Different Types of Shift Work Affect Nurses' Sleep Quality and Stress Hormone Levels

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Abstract

Nurses working rotating shifts had a significantly lower sleep quality score of 73 compared to 77 for those on day shifts.

A total of 140 nurses participated in the study conducted in Croatia in 2025.
Most nurses (98.6%) had a neutral chronotype.
Rotating-shift nurses exhibited higher morning cortisol levels compared to day shift nurses, with medians of 431.6 nmol/L versus 355.15 nmol/L.
In the rotating-shift group, morning cortisol levels were positively correlated with age and years of service, but negatively correlated with circadian rhythm.
Sleep quality and cortisol regulation disruptions were observed among rotating-shift nurses, but cortisol levels normalized after two nights of rest.

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Rotating shift work is a common occupational stressor among healthcare professionals. This study aimed to examine the impact of shift work on sleep quality and cortisol levels among nurses. A prospective observational study was conducted in Croatia in 2025, involving 140 nurses. Sleep quality was assessed using the Fitbit Charge 3 smartwatch over eight consecutive days, and blood cortisol was measured at two time points. Most nurses (98.6%) had a neutral chronotype. Nurses who work day shifts (DSN) achieved significantly higher sleep scores compared with rotating-shift nurses (RSN) (77, IQR 75-80 vs. 73, IQR 68-76; Mann-Whitney U test,< 0.001). RSN also had significantly higher morning cortisol levels at the first measurement (median 431.6, IQR 351.3-496.2 vs. 355.15, IQR 254.9-434.2) nmol/L;< 0.001). In the RSN group, morning cortisol levels at the first measurement were positively correlated with age and years of service, and negatively correlated with circadian rhythm. Smartwatch-based assessments demonstrated that rotating shift work is associated with poorer sleep quality and transient disruption of cortisol regulation. Notably, cortisol levels in rotating-shift nurses returned to levels comparable to those of DSN after two nights of rest, indicating substantial reversibility of the hormonal response. These findings highlight the short-term physiological impact of shift work and underscore the importance of optimizing work schedules and implementing strategies to reduce long-term health risks. p p

Effects of Shift Work Type on Sleep Quality and Cortisol Regulation Among Nurses: A Prospective Observational Study.

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