In the evening on the first and third working days, cortisol levels of night shift nurses were significantly higher
than those of the day shift nurses, and in the morning on the second working day, cortisol levels of night shift nurses were significantly lower than that of the day shift nurses.
Our findings showed that salivary components indeed reflect the biochemical mechanisms of impaired circadian
rhythm induced by a 16 h night shift. Underpinning our findings are studies that demonstrate similar circadian
variation in cortisol levels and other salivary biomarkers such as α-amylase activity, sIgA levels, and
chromogranin A levels that show morning spikes and evening lows.