Lighting and daylighting for visual comfort and energy efficiency

Light influences the daily rhythm and well-being of humans in a physiological, psychological and biological way. Light doesn’t only enable humans to see; beside the visual rods and cones the human eye also contains (recently discovered) non-visual photoreceptors (Berson et al., 2002). Supported by light perception, the human biological clock system tells the human body when to regulate multiple body functions such as body temperature, sleep patterns, cognitive performance, mood, well-being, and the release and production of hormones. Compared to the sensitivity of the visual system (V), the maximum effect of the non-visual system (C) is shifted towards the shortwave radiation and has its peak in the blue part of the spectrum.