||This paper deals with the problem of light pollution and its potential impact on human body. Loss of darkness during the night has a negative effect on the environment, animals, plants and humans. Concerning humans, the light during the night can lead to desynchronization of circadian rhythms with subsequent lower production of sleeping hormone called melatonin. In addition to the negative impact on organisms, there is also economical effect of wastage of lighting during the night. Pollution caused by the occurrence of light during the night is relatively new term, which has been perceived very roughly so far. That is probably the reason, why Slovak legislation deals with this problem very roughly. Some limitation levels of illuminance of billboards were stated, but the legislation doesn ́t deal with the effect of the occurrence of higly influential light during the night on people at their homes.