Effect of Two Different Lighting Environments on Urinary Neopterin and Sulphatoxymelatonin in an Experimental Night Shift Model

Abstract

Regular night shift activities are associated with a series of adverse effects (e.g. chronic fatigue, increased yield loss rates, diseases) related to a disturbed circadian rhythm of the employee. According to current knowledge, the human circadian system is affected by visible light in the short wavelength range. In the present study, we investigated the effects of reduced short-wavelength components in the lighting environment of an office workplace on circadian markers, symptoms of lassitude, and personal mood in an experimental night shift setup. Nocturnal urinary neopterin excretion was different from known circadian rhythms under both filtered test light and bright light conditions. By contrast, urinary sulphatoxymelatonin concentrations could be adjusted to a normal diurnal profile in the test light environment. Mood rating inventories did not result in differences in the subjective perception between the two lighting environments with respect to the dimensions of "Activity", "Concentration, "Deactivation", and "Fatigue". In addition, changes in signs of vigour and weariness in the course of each night of the study were equally pronounced in test light and bright light. In conclusion, the present study shows that light with reduced short-wavelength components maintains the nocturnal profile of sulphatoxymelatonin but simultaneously exerts a wearisome effect on the participants. Therefore, a general implementation of test light to illuminate night shift workplaces implies further investigations.

Keywords

• circadian rhythm
• lighting environment
• neopterin
• shift work
• sulphatoxymelatonin