Light and Life Quality: Psychophysiological Effects of LED Lighting Scenarios
Light supports the synchronisation of important circadian rhythms. When staying mainly outside it’s sunlight that helps to synchronize the rhythms. The usage of chronobiologically optimized lighting systems promises a stabilization of circadiac phases. Within the scope of this project guest of a wellness hotel were randomly assigned to two groups with different lighting conditions. One of the groups spent each two days and nights under normal, hotel typical lighting conditions. For the other group the hotel rooms and areas were modified with a chronobiological lighting, i.e. the light was adapted to the time of day. Thus, this group spent its two-day stay under lighting conditions that is orientated towards the brightness and color gradient of sunlight.
During daytime, these hotel guests were exposed to an especially bright lighting, whereas during the evening hours the illumination was notably reduced. Apart from the brightness of the light especially its color played a central role in the adaption of the lighting. Following this, the daytime lighting was adjusted to a bluish cold white and in the evening hours it was adjusted to a reddish warm white. The impact that this adjusted lighting had was measured using physiological methods such as long-term ECG and motion sensors. In addition to that saliva samples of the participants were collected regularly to measure the concentration of the stress hormone cortisol and the sleep hormone melatonin.