Changes in serum free testosterone, sleep patterns, and 5-alpha-reductase type I activity influence changes in sebum...

Sebum is thought to play an important role in acne vulgaris and sebum excretion rate (SER) is often used as a marker of efficacy in acne studies. This study explored factors that could induce intra-subject variability in SER.

SER was measured twice, 7 days apart, on the forehead of 40 healthy subjects. At each visit, the following parameters were also evaluated: serum androgen levels, 5-alpha-reductase type I gene expression, forehead temperature, sleep habits, diet, facial washing routine, and UV exposure.

There was a positive correlation between the time subjects fell asleep on Day 0 and the change in SER for the left (P = 0.010; R = 0.402) and right sides (P = 0.002; R = 0.467) of the forehead. There was a significant inverse correlation between SER and 5-alpha-reductase type 1 expression and between free testosterone levels and 5-alpha-reductase type 1 expression. In sub-analyses performed on men and women, these correlations were only significant for women.

Variations in sleep patterns, free testosterone, and 5-alpha-reductase type 1 activity are associated with changes in sebum excretion in women. This could explain some of the inter-subject variability in SER measured between visits in clinical studies.