Modulation of lighting intensities and color temperature: Effects on melatonin and cognitive performance

High-quality workplace illumination exerts a number of benefits with respect to the employees’ productivity as well as the maintenance of a physiological circadian rhythm and well-being. In the present study, two different lighting environments were investigated, one representing a standard lighting design in a window-less office (500 lux, 4000 K), the other providing a variable setup (500–1800 lux, 6500 K). The variable lighting system resulted in the expected effects on parameters of circadian rhythm (e.g. a decreased serum melatonin concentration at the end of each day of the study). However, the test light with its variable intensities and higher color temperature did not turn out to be superior to the regular workplace illumination.