Exploratory Study of Intra and Inter-subject Variability in Sebum Excretion Rate

A total of 40 subjects with a sebum excretion rate of at least 4 will be included. Subjects will be seen at Day 0 and Day 7. Casual sebum measurements will be performed at least 2 hours after washing the face in the morning with a Sebumeter® following a 30-second application of a Sebumeter® Measurement Cartridge to the forehead. Sebum excretion rates will be measured with Sebutape® applied to the right and left forehead at each visit. Each Sebutape® will be scanned and the area covered by sebum, seen as gray-black dots on the scanned Sebutape®, will be measured by an image analysis software. Circulating levels of free testosterone and DHEAS will be measured at each visit. A skin biopsy behind an ear will be performed at Day 0 and Day 7 to measure gene expression of the 5-α-reductase type 1. On Day 0 and Day 7, subjects will be required to take a 24-hour recall questionnaire. On Day 0 and Day 7, subjects will be questioned about the time of sleep induction, their total sleep time for the night preceding the visit, facial washing routine and the number of hours of direct and indirect UV exposure in the past 24 hours. On Day 0 and Day 7, subject's forehead skin temperature will be measured.