ABSTRACT Until the end of the 19th century, when artificial light sources came into use, people organized their whole life according to sunlight and spread it throughout the day. Human beings carry out their life, work, and production in indoor environments by bringing sunlight indoors as much as possible. However, today, people have to spend most of their time in closed areas without sunlight. Indoor areas where light cannot reach and artificial light sources, necessary during the night due to need, have developed over time and reached a very important level, especially in the 20th century.