(Day)light is the main reason we can perceive our surroundings. Light is not only about illuminance levels and luminance, but also about material, contrast, orientation and mainly the perception of the user. The type of light and the position of light has a major impact on how we perceive a room, and therefore on our state of mind. Besides that we need light to see our environment, light is also important for the control of various body processes and hormones at a rhythm of 24 hours (circadian). Especially for the elderly and people with physical or mental limitations, who do not get enough exposure to natural light in their daily routines, a good lightning design of a room is very important. The lack of (natural) light as declarant for time and rhythm can lead to sleep disorders, chronic fatigue or depression.