Daylight, artificial light and people in an office environment, overview of visual and biological responses

The study was carried out to show how bright light affects intellectual mnestic performance alertness, mood and psychophysiological variables in order to understand the mechanism of bright light which is still unclear. 15 healthy normal volunteers (8 males, 7 females) aged 22-34 years (mean 27) participated in the study. Exposure to bright light (2500 lux) or dim light (500 lux) was intermittent for 4 h between 9 a.m. and 5 p.m. Psychometric investigations for assessment of noopsychic variables, such as attention and concentration on the one hand, and thymopsychic variables, such as drive, on the other hand, as well as flexibility and psychophysiological measurements were carried out before, as well as 1, 2, 4, 6 and 8 h after baseline. As compared to the dim-light condition, subjects who were exposed to biologically-active light showed an improvement of noopsyche in the 6th and 8th hour. Also, the subjective thymopsyche revealed an improvement lasting for the whole investigation period. Psychophysiological measurements reflected an improvement of central and autonomous activation, which was parallel to the improvement of cognition and of well-being. However, biologically-active light did not affect flexibility.