Margot Morssinkhof

Appendix 302 who underwent sex hormone interventions, the associations between sleep and mood symptoms were less clear. We also studied the association between sex hormones, depression and sleep in Chapter 2 and Chapter 3. In Chapter 2, our results show that the differences in insomnia symptoms between OC users and naturally cycling participants were not different in participants with a history of mood disorders or with a current mood disorder. In Chapter 3, our findings show that at the start of GAHT insomnia symptoms, such as trouble falling asleep and waking up at night, were not associated with depressive symptoms. Summary The results in this thesis show that both OCs and GAHT can affect depressive symptoms. OCs can increase depressive symptoms, although effects differ between individuals. The effects of GAHT differ between masculinizing GAHT, which temporarily decreases lethargy symptoms after 3 months, and feminizing GAHT, which slightly increases low mood symptoms after 12 months. Exogenous hormones containing female sex hormones (i.e., OCs or feminizing GAHT) can have a more adverse effect on depressive symptoms, although we found small effects and effects differ between individuals. Our studies on sleep show that both OCs and GAHT can have a small effect on subjective sleep, that masculinizing GAHT can affect slow wave sleep and REM-sleep, and that both masculinizing and feminizing GAHT can affect chronotype. In the studies on OCs, we have conducted multiple cross-sectional betweensubject comparisons. This means that in some studies, we compared a group of long-term OC users with a group of participants who chose not to use OCs. It is possible that the group of OC users experiences fewer side effects, and that we therefore underestimated the effects of OCs: this is an important limitation in our studies. In the studies on GAHT, an important limitation is that we could not account for changes in psychosocial factors in participants, including changes in body image, social support and discrimination after starting GAHT. It is possible that these changes also have affected participants’ sleep and mood.

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