This study examined separate inattentive, hyperactive, and impulsive dimensions of attention-deficit/hyperactivity disorder (ADHD), as well as sluggish cognitive tempo (SCT) symptoms, in relation to college students' sleep functioning. Participants were 288 college students (ages 17-24; 65 % female; 90 % non-Hispanic White; 12 % self-reported having an ADHD diagnoses) who completed measures of ADHD/SCT symptoms and sleep functioning. Participants reported obtaining an average of 6.8 h of sleep per night (only 26 % reported obtaining ≥8 h of sleep) and having a sleep onset latency of 25 min. 63 % were classified as "poor sleepers," and poor sleepers had higher rates of ADHD and SCT symptoms than "good sleepers". Path analysis controlling for ADHD status and psychiatric medication use was used to determine associations between psychopathology and sleep functioning domains. Above and beyond covariates and other psychopathologies, hyperactivity (but not impulsivity) was significantly associated with poorer sleep quality, longer sleep latency, shorter sleep duration, and more use of sleep medications. SCT symptoms (but not inattention) were significantly associated with poorer sleep quality and increased nighttime sleep disturbance (e.g., having bad dreams, waking up in the middle of the night, feeling too cold or too hot). Both inattention and SCT were associated with greater daytime dysfunction. Regression analyses demonstrated that hyperactivity predicted sleep quality above and beyond the influence of daytime dysfunction, and inattention and SCT predicted daytime dysfunction above and beyond sleep quality. Further studies are needed to examine the interrelations of nighttime sleep functioning, ADHD/SCT, and daytime dysfunction, as well to elucidate mechanisms contributing to related functional impairments.