Chronotype changes after sex hormone use 207 Figure 7.2. Sleep duration (line) and sleep-corrected midpoint of sleep on free days (point) before GAHT (baseline; displayed as the top orange bar) compared to after 3 months of GAHT (displayed as the bottom green bar). The Y-axis displays the groups, the X-axis displays the sleep duration (as a line) and midpoint of sleep (as a point) in hours. 4. Discussion With this study we prospectively investigated the effects of sex hormone use on chronotype in transgender GAHT users. Our results show the transmasculine participants, who were assigned female at birth, developed a later chronotype after the first 3 months of testosterone. In contrast, transfeminine participants, who were assigned male at birth, developed an earlier chronotype after 3 months of estrogens and anti-androgens. Taken together, our results indicate that the use of masculinizing or feminizing sex hormones can influence midpoint of sleep in an opposite direction, which is in line with chronotype differences seen in the cisgender population. Our findings of a later chronotype after 3 months of masculinizing sex hormone use and an earlier chronotype after 3 months of feminizing sex hormone use are in concordance with our hypotheses. Previous research found that testosterone was associated with a later chronotype: salivary testosterone levels in cisgender men were found to be associated with a later chronotype (Randler et al., 2012), and women with PCOS, who have elevated testosterone levels, also have a later chronotype than women
RkJQdWJsaXNoZXIy MTk4NDMw