Accumulating evidence suggests an important role of sleep disturbance in posttraumatic stress disorder (PTSD) (Babson & Feldner, 2010). Indeed, both subjective and objective sleep disturbance is evident in PTSD (Straus, Drummond, Nappi, Jenkins, & Norman, 2015), and sleep disturbance prior to trauma exposure predicts the development of PTSD (Gehrman et al., 2013). Despite considerable evidence for a link between sleep disturbance and PTSD, limited research has examined specific mechanisms that may account for this relationship. Once such process is attentional control, or the ability to flexibly shift and focus attention (Derryberry & Reed, 2002). Sleep disturbance is known to impair cognitive function (Van Dongen, Maislin, Mullington, & Dinges, 2003), and deficits in attention control have been linked to PTSD (Olatunji, Armstrong, McHugo, & Zald, 2013). The present study examined the relative effects of two facets of attentional control, focusing and shifting attention, on the relationship between sleep disturbance and PTSD. A sample of combat-exposed veterans (n = 72) completed self-report measures of sleep disturbance (Insomnia Severity Index; Morin et al., 2011), attentional control (Attentional Control Scale; Derryberry & Reed, 2002), and PTSD symptoms (PTSD Checklist; Weathers et al., 1993). Mediation analyses using the PROCESS macro for SPSS (Hayes 2013) revealed a significant indirect effect of shifting, but not focusing attentional control on the relationship between sleep disturbance and PTSD symptoms. Specifically, the 95% bias-corrected bootstrap confidence interval for the specific indirect effect of shifting attentional control (ab = .12) based on 10,000 bootstrap samples did not include zero (.01 to .34). In contrast, the 95% bias-corrected bootstrap confidence interval for the specific indirect effect focusing attentional control (ab = .02) based on 10,000 bootstrap samples did include zero (-.15 to .21), indicating no significant indirect effect of focusing attentional control. These findings suggest that sleep disturbance may lead to difficulty disengaging attention, which may contribute to the maladaptive orienting of attention towards threat-relevant stimuli evident in PTSD. Additional research is necessary to examine this effect in a prospective design.