['Women with histories of childhood sexual abuse (CSA) have higher rates of sexual difficulties, as well as high sympathetic nervous system response to sexual stimuli.', 'The study aims to examine whether treatment-related changes in autonomic balance, as indexed by heart rate variability (HRV), were associated with changes in sexual arousal and orgasm function.', 'In study 1, we measured HRV while writing a sexual essay in 42 healthy, sexually functional women without any history of sexual trauma. These data, along with demographics, were used to develop HRV norms equations. In study 2, 136 women with a history of CSA were randomized to one of three active expressive writing treatments that focused on their trauma, sexuality, or daily life (control condition). We recorded HRV while writing a sexual essay at pretreatment, posttreatment, and 2-week, and 1- and 6-month follow-ups; we also calculated the expected HRV for each participant based on the norms equations from study 1.', 'The main outcome measures used were HRV, Female Sexual Function Index, Sexual Satisfaction Scale--Women.', 'The difference between expected and observed HRV decreased over time, indicating that, posttreatment, CSA survivors displayed HRV closer to the expected HRV of a demographics-matched woman with no history of sexual trauma. Also, over time, participants whose HRV became less dysregulated showed the biggest gains in sexual arousal and orgasm function. These effects were consistent across condition.'] Are changes in Autonomic Nervous System Activity Associated with Changes in Sexual Function in Women with a History of Childhood Sexual Abuse?