A growing literature shows prominent sex effects for risk for PTSD and associated medical comorbid burden. Prior research indicates that PTSD is associated with reduced slow wave sleep (SWS), which may have implications for overall health, and abnormalities in REM sleep, which have been implicated in specific PTSD symptoms, but most research has been conducted in male subjects. We therefore sought to compare objective measures of sleep in male and female PTSD subjects with age and sex-matched control subjects. We used a cross-sectional, 2×2 design (PTSD/control × female/male) involving 83 medically healthy, non-medicated adults aged 19–39 in the inpatient sleep laboratory. Visual analysis of EEG demonstrated that PTSD was associated with lower SWS duration (F(3,82)=7.63, p=.007) and SWS percent (F(3,82)=6.11, p=.016). There was also a group by sex interaction effect for REM duration (F(3,82)=4.08, p=.047) and REM percent (F(3,82)=4.30, p=.041), explained by greater REM sleep in PTSD females as compared to control females, a difference not seen in male subjects. Quantitative EEG analysis demonstrated that PTSD was associated with lower energy in the delta spectrum (F(3,82)=6.79, p=.011) in NREM sleep. SWS and delta findings were more pronounced in males. Removal of PTSD subjects with comorbid MDD, who had greater PTSD severity, strengthened delta effects but reduced REM effects to non-significance. These findings support prior evidence that PTSD is associated with impairment in the homeostatic function of sleep, especially in men with the disorder. These findings suggest that group by sex interaction effects on REM may occur with more severe PTSD or with PTSD comorbid with MDD.