Objectives Individuals with insomnia often report aspects of perfectionism and symptoms of anxiety and depression. Investigation of these factors together has been limited. As such, the aim of the present study was to examine the extent to which the association between perfectionism and insomnia symptoms was mediated by anxiety and depression, concurrently and longitudinally. Methods Seventy-six members from the general-population participated at baseline. Data from 57 participants were subsequently analysed at twelve-month follow-up. Insomnia symptoms were assessed using The Insomnia Severity Index (ISI). Perfectionism was assessed using two Multidimensional Perfectionism Scales (F-MPS; HF-MPS). Symptoms of anxiety and depression were assessed using The Hospital Anxiety and Depression Scale (HADS). Correlational analysis examined longitudinal associations between perfectionism and insomnia symptoms. Hierarchical regression analysis examined whether significant associations remained after controlling for anxiety and depression. Results Baseline insomnia symptoms were associated with future doubts about action. Further, this relationship was mediated by preceding symptoms of anxiety and concurrent symptoms of insomnia. Similarly, baseline insomnia symptoms were also associated with future parental criticism. However this relationship was partially mediated by preceding symptoms of anxiety, and was not mediated by concurrent insomnia symptoms. Conclusions Symptoms of insomnia appear to be related to an increase in negative perfectionistic thinking in the form of doubts about action and parental criticism, however these relationships appear to be mediated by symptoms of anxiety. Therefore, treatments for insomnia should address anxiety symptoms with the prospect of preventing the accentuation of aspects of perfectionism due to poor sleep.