Salivary cortisol levels were attenuated in night-shift workers during their working hours compared to day-shift workers.
Night-shift workers exhibited a normal circadian rhythm of salivary cortisol but with reduced levels during work hours.
Sleep duration was shorter for night workers compared to those on day shifts.
Night workers experienced greater negative than day workers.
Intervals between night shifts may aid in the recovery of the hypothalamic-pituitary-adrenal axis.
Promoting sleep hygiene and healthy life habits could be beneficial for night-shift workers.
Simplified
OBJECTIVES: Night-shift work has been associated with several negative effects on worker's health, possibly due to circadian desynchronization, sleep deprivation and suppression of nocturnal melatonin secretion including exposure to light during the work shift. The objective of this study was to evaluate the impact of fixed night-shift work versus day-shift work on the sleep-wake cycle and on the night and day levels of cortisol and melatonin.
MATERIAL AND METHODS: Saliva samples were obtained from 36 individuals, 19 day workers (12 women and 7 men) and 17 night workers (12 women and 5 men) from a university hospital in southern Brazil, with no history of chronic diseases. Demographic and personal information were obtained through a self-administered questionnaire and sleep information by the Munich chronotype questionnaire.
RESULTS: Salivary cortisol showed normal circadian rhythm in day- and night-shift workers, but was attenuated in night-shift workers during their working hours and on leave days. Night workers sleep fewer hours at night and have higher negative than day workers.
CONCLUSION: Intervals between night shifts can be beneficial for the recovery of the hypothalamic-pituitary-adrenal axis, minimizing the negative effects on workers' health, in addition to a preventive approach to aspects related to sleep hygiene and healthy life habits.
Key numbers
3.68 hours
Sleep Duration Decrease
Average sleep duration on working days for night-shift workers
0.97%CI: 0.74; 1.21 vs. 0.21%CI: 0.15; 0.26
Cortisol Levels Comparison
Cortisol levels in day-shift vs. night-shift workers at different times
0.003
Negative
P-value for the difference in between day- and night-shift workers
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