(PS8-3) Examining Intraindividual Sleep Variability in Survivors of Sexual Assault

Abstract Text: Although most research has focused on characterizing nightly sleep on average, greater intraindividual variability (IIV) in sleep (i.e., fluctuations from night to night) is prevalent and associated with negative health outcomes. Accordingly, reducing IIV in sleep is a primary target of cognitive-behavioral therapy for insomnia. Initial evidence suggests IIV in sleep is elevated among some trauma survivors, including military veterans with posttraumatic stress disorder (PTSD). However, less is known about IIV in sleep among sexual assault survivors, who also frequently experience sleep disturbances, or among those with comorbid trauma and alcohol misuse, which could further amplify sleep irregularity. To address this gap, this study identified factors that could contribute to elevated risk for IIV in sleep among sexual assault survivors with comorbid PTSD symptoms and alcohol misuse. Six hypothesized risk factors—PTSD symptom severity, alcohol misuse severity, age at sexual assault, years since sexual assault, racial/ethnic identity, and sexual identity—were tested as predictors of greater IIV in sleep duration, sleep efficiency, and wake after sleep onset (WASO). Participants were 82 young adult cisgender women who experienced sexual assault and reported comorbid PTSD symptoms and alcohol misuse (73.2% non-Hispanic White, 56.1% heterosexual). Participants completed baseline self-report questionnaires and three weeks of naturalistic sleep assessment via actigraphy (i.e., wearable devices that continuously collect movement data to detect sleep-wake patterns). Three latent random variability models examining each actigraphy-based sleep outcome were estimated with multilevel structural equation modeling in Mplus. Less time since sexual assault predicted greater IIV in sleep duration [b = -0.07, 95% CI (-0.121, -0.008], WASO [b = -0.07, 95% CI (-0.123, -0.005], and sleep efficiency [b = -0.07, 95% CI (-0.121, -0.013] after controlling for all other predictors. Sexual minority women reported lower IIV in sleep duration than heterosexual women [b = -0.34, 95% CI (-0.675, -0.005]. There were no other significant unique predictors. These findings suggest that sleep irregularity may be a hallmark of the acute post-assault period, highlighting the potential benefits of early interventions to enhance sleep regularity to promote trauma recovery, particularly among heterosexual women. In addition, the observed differences in sleep variability by sexual identity underscore the need for further research examining the unique protective factors that may buffer against irregularity in sleep duration among sexual minority women.