Individuals with sleep-disturbances, specifically insomnia, often exhibit aspects of perfectionism, and symptoms of anxiety and depression, however the investigation of these factors together has been diminutive. The present study examined the mediating role of anxiety and depression on the associations between sleep-disturbances, insomnia-severity and aspects of perfectionism. Eighty-six participants (Age: M = 25, SD = 10.02; 80% female) were assessed using the Pittsburgh Sleep Quality Index (PSQI) and Insomnia Severity Index (ISI). Participants also completed two Multidimensional Perfectionism Scales (F-MPS; HF-MPS), and the Hospital Anxiety and Depression Scale (HADS). Poor-sleepers demonstrated significantly higher scores on the F- MPS subscale doubts-about-action compared to normal-sleepers (t (84) = 2.54, P = 0.01). Additionally, global PSQI scores were significantly associated with doubts-about-action (r = 0.22, P = 0.04). Insomnia-severity was significantly associated with the F-MPS subscales of doubts-about-action (r = 0.32, P = 0.01), concern- over-mistakes (r = 0.26, P = 0.02), and parental-criticism (r = 0.30, P = 0.01). Hierarchal multiple-regression analyses, separately exam- ining the global PSQI and insomnia-severity scores, demonstrated that when anxiety and depression were controlled for, none of the previous associations remained significant. The results indicate that: 1. bothincreasedsleep-disturbanceandinsomniaseverityappearto be associated with increased doubts-about-action; 2. increased insomnia-severity also appears to be associated with increased concern-over-mistakes, and parental criticism; and 3. these associations are mediated by anxiety and depression. These results could suggest that treatments for sleep-disturbance and insomnia should address anxiety and depressive symptoms, with the prospect of alleviating aspects of perfectionism, specifically doubts-about-action, concern-over-mistakes, and parental criticism, that may perpetuate pre-sleep arousal, consequently disturbing sleep.