RecruitingRadiation therapyDNA Repair Activity in the Skin of Day and Night Shift WorkersThe purpose of this study is to test how the skin of night shift workers responds to artificial sunlight (ultraviolet B radiation; UVB) at two different times of the day in comparison to normal day shift workers. After the skin biopsies are obtained, they will be brought to the laboratory to be exposed to UVB radiation and to measure UVB responses.