The Effect of Night-Shift Work on the Level of Urinary 6-Sulphatoxymelatonin in Men Over Five Days

Abstract

Night-shift work may adversely affect health. This study aimed to assess the effect of night-shift work on the level of urinary 6-sulphatoxymelatonin. Repeated measures of urinary 6-sulphatoxymelatonin on the morning before night-shift work and after first, third and fifth night-shift work was undertaken in 29 males, Malay, day-night-shift workers. A total of 29 male workers participated in this study. Median age was 29 years old. The highest level of urinary 6-sulphatoxymelatonin was at time point 1, followed by a significant reduction from time point 1 to time point 2. Subsequently, there was a progressive increase of urinary 6-sulphatoxymelatonin from time point 2 to 4. However, the urinary 6-sulphatoxymelatonin did not normalise at time point 4 and remained lower than the baseline reading taken at time point 1. This appears to suggest that workers were not able to achieve circadian adaptation to night-shift work even after five days of night-shift work. Findings from the current study could be useful as a reference, in developing strategies to enhance circadian adaptation to night-shift work.