Lighting Quality and Human Health Problems in Man-made Environment

In this paper, the features and types of lighting in different environments have been reviewed to highlight their effects on the biological human body. Secondly, strategies for domesticating healthy daylight in buildings and design of light sources have been graphically presented to define their critical zones. Next, the mechanism of body organs against light considered in different environments with different values. Finally, the rate of antidepressants consumption and average hours of sunlight per year in the most populous cities of twenty-one countries presented that shows an inverse relationship between antidepressants consumption and average hours of sunlight. Inappropriate lighting may harm physiological systems such as the visual, the nervous and the endocrine, the pineal, and the pituitary systems, as well as cardiac activity and skin conductance. It is noticeable that each problem creates or increases stress and depression. Natural daylight produces serotonin which is called the happiness hormone. Therefore, the rate of depression among residents of southern blocks, who absorb more daylight, is less than other blocks in winter. The most effective factor to obtain daylight and its pertinent quality is appropriate orientation. On the other hand, indoor lighting quality defines the level of visual comfort, which is measured and evaluated under the Relative Visual (RV) Performance model.