The investigation of chronobiological aspects of non-visual effects of light in humans.

The chronobiological studies on non-visual lighting effects presented in this postdoctoral thesis show qualitative differences of the same depending on age, long- and short-term adaptation. Chromatic pupillometry was also used to examine the extent to which the pupil reflex on light is suitable for use as a marker for melanopsin-dependent functions in healthy people and patients with visual impairment. An essential contribution of the presented works lies in showing concrete meanings of the ‘prior light history’. By this term we mean the direct and indirect after-effects of light exposure in humans, for example, the effects on cognitive performance in the evening in accordance with the lighting conditions in the afternoon or the greater alertness in the evening as a result of repeated light exposures with brighter lighting on the previous evenings. In the ultra-short-term range, we demonstrated by means of the evoked potentials in the EEG that depending on the spectral composition of the light stimuli, a different neuronal activation took place. This could be important for situations in which very quick reactions are required. In this interdisciplinary and partly new research field, many exciting questions remain unanswered. How does long-term (too) weak lighting affect our performance and health during the day? The topic covered concerns both basic research and practical application and will certainly occupy and influence us in the next few years. The development and validation of chromatic pupillometry presented in two of his own works and their use for chronobiological questions could help to further advance the development of tailor-made (lighting) conditions for different populations and patients.