Background: Several studies have shown the possible link between trauma and sleep disturbances, particularly in anxiety disorders. This issue could be because sympathetic hyperarousal is central to both disorders, probably caused by a dysregulation of the noradrenergic system. This study aimed to establish if the comorbidity with complex post-traumatic stress disorder (cPTSD) is associated with sleep disturbances in panic disorder (PD) and if the presence of poor sleep quality is associated with a higher psychopathological burden. Methods: Participants (N = 211) with PD completed the International Trauma Questionnaire concerning their most troubling experience, the Hamilton Anxiety Rating Scale (HAM-A), and the Pittsburgh Sleep Quality Index (PSQI) to assess anxiety symptoms and sleep disturbances, respectively. Results: The sample was divided into two subgroups based on the presence of cPTSD. No significant differences emerged in the bivariate analyses for what concerns sociodemographic features. As for the scores of the psychopathological scales, the analysis highlighted statistically significant differences between the subgroups. Subjects with cPTSD reported significantly higher HAM-A total scores. As for the disturbances in self-organization (DSO) and PSQI scores, these were all significantly higher in the cPTSD subsample. At the logistic regression, the presence of cPTSD was inserted as the dependent variable, while the PSQI scores of the subscales evaluating subjective sleep quality, sleep duration, sleep efficacy, and the use of hypnotics were used as independent variables. The presence of cPTSD was significantly associated with the PSQI subscores for subjective sleep quality and use of hypnotics. Conclusions: Patients with PD exhibit more severe sleep disturbances and a higher anxiety burden when experiencing prolonged trauma. Therapeutic advances are needed in this field to target these symptomatologic domains.