Search

The present studies examined the feasibility and acute alerting effects of additional in-vehicle lighting within a passenger car. These factors were examined during morning driving (Study 1) and evening driving (Study 2). In a balanced within-subjects design, 37 participants drove a test car two times in the morning or in the evening. The test vehicle was equipped with either a daylight-supplementing interior lighting system or a placebo system, which participants were told would refresh the air. Both studies used identical protocols, and participants participated either in Study 1 ( n = 18) or Study 2 ( n = 19). In both studies, corneal illuminance levels were recorded while driving. Feasibility of the systems was assessed using subjective ratings. Efficacy outcomes were spindle rates in the alpha bandwidth of electroencephalogram recordings, performance on a psychomotor vigilance task and subjective sleepiness ratings. In both studies, daylight-supplementing significantly increased corneal illuminances while driving and did not cause any negative visual side-effects. Study 1 revealed lower spindle rates while driving under daylight-supplementing lighting, indicating that drivers had higher physiological alertness when exposed to additional light in the morning. This alerting effect of daylight-supplementing lighting, however, was not observed in Study 2. In both studies, performance on the psychomotor vigilance task as well as subjective sleepiness ratings did not significantly differ between the experimental conditions. The present studies provide novel evidence for the feasibility and positive impact of daylight-supplementing in-vehicle lighting systems on the physiological alertness of drivers under naturalistic driving conditions. Further studies are warranted to evaluate carry-over effects of increased alertness on road safety measures.

The presentation of merchandise often happens undifferentiated with a high level of brightness causing high energy demand. For human perception this results in intense light pressure and risk of increased glare. We developed and investigated lighting concepts with various lighting distributions and colour contrasts which were investigated in a perception study. 30 participants rated homogeneous, zonal single-coloured and zonal colour-contrasted lighting scenes regarding their brightness impression at two 1:10 scale shop models. Compared to homogeneous reference lighting scenarios, the zonal lighting scenarios can be operated with about 30% reduced overall room illuminance values while being perceived as similar bright.

An artificial skylight has been developed which aims at creating an impression of a daylight opening in the ceiling by means of an artificial sunspot and a blue sky with perceived infinite depth. It is the goal of this work to compare and quantify the perceived room atmosphere created by this artificial system with that created by a conventional lighting system. A total of 100 subjects participated in a randomized controlled study within which the short-term effects on room lighting- and room atmosphere-appearance were determined. Both the artificial skylight and the resulting room atmosphere were perceived as very natural and attractive. Thus, the first strong evidence for the expected positive effects of this artificial skylight was determined.

Permanent morning shift workers often suffer from impaired sleep and complain about increased fatigue during the day due to an early rising time in the morning. A controlled field investigation with female permanent morning shift workers was conducted, which evaluated the acute, monthly and seasonal psycho-physiological and productivity-related impacts of a dynamic ambient lighting scenario. Dynamic lighting had an acute psycho-physiological calming effect and positively influenced sleep latency and anxiety/depression ratings. Finally, productivity (decreased mean relative handling time) was increased during the winter. This field study contributes to the growing knowledge about biological lighting impacts during shift work. Furthermore it indicates lighting effects on productivity-related and subjective measures for a sleep-deprived working population.

Workplace illumination is of paramount importance in determining the employee's productivity and well-being. Moreover, light exerts non-visual effects with respect to biological rhythms. In this study, we investigated the impact of different lighting conditions (500-1800 lx, 6500 K; 500 lx, 4000 K) on sulphatoxymelatonin (aMT6-s) and subjective mood in an experimental office accommodation. Urinary aMT6-s concentrations were significantly decreased at all days of the experiment in both lights. On day 3, differences between aMT6-s concentrations in specimen collected at 05:00 p.m. and at 09:00 a.m. were significantly higher under variable lighting conditions. Analyses of a mood rating inventory revealed a benefit of variable light with respect to the dimensions of "Activity", while "Deactivation" and "Fatigue" were increased in regular light on day 1. "Activity", "Concentration", and "Deactivation" changed in opposite directions when comparing variable with regular illumination on two consecutive days. In conclusion, variable light exerts a potential advantage in indoor office accommodations with respect to subjective mood, although no unequivocal differences in the profile of aMT6-s were found as compared to regular light.

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.