<p>Although most research has focused on average indices of sleep, night-to-night variability in sleep (intraindividual variability; IIV) is prevalent and associated with negative health outcomes. This study examined predictors of IIV in sleep among young adult women with posttraumatic stress disorder (PTSD) symptoms and hazardous alcohol use following sexual assault, a population that may be at elevated risk for sleep variability. Specifically, PTSD symptoms, alcohol use problems, 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 (<i>N</i> = 82) completed baseline questionnaires and three weeks of naturalistic sleep assessment via actigraphy. Three latent random variability models examining each sleep outcome were estimated with multilevel structural equation modeling in Mplus. Less time since sexual assault predicted greater IIV in sleep duration, sleep efficiency, and WASO after controlling for all other predictors. Sexual minority women reported lower IIV in sleep duration than heterosexual women. No other predictors were significant. These findings that multiple dimensions of sleep are more irregular soon after a sexual assault highlight a potential window for early intervention. Specifically, interventions that target sleep consistency may support recovery during this time, particularly for heterosexual women who also showed greater variability in sleep duration.</p>