Objective.To investigate if sleep disturbances may affect treatment outcomes of patients with panic disorder (PD).Methods.Eighty-five PD outpatients with no Axis I comorbidity for mood disorders completed a baseline assessment (T1) and were evaluated after 3 (T2), 6 (T3) and 12 months (T4), with the Panic Disorder Severity Scale (PDSS) total score as outcome measure during a 12-month naturalistic follow-up. Patients were assessed with the Mood Spectrum Self-Report (MOODS-SR, Lifetime Version), and the PDSS.Results.Forty-three patients (50.5%) met criteria for remission (PDSS<5) and 42 (49.5%) for no remission. In a logistic regression model withremissionas the dependent variable, MOODS-SRsleep disturbanceswas the only determinant for a lower likelihood of PD remission. The items accounting for this result were the following:Repeated difficulty falling asleep(chi-square = 4.4; df = 1;p= 0.036), andRepeatedly waking up in the middle of the night(chi-square = 5.2; df = 1;p= 0.022).Conclusion.Lifetime sleep disturbances would represent a cue of mood spectrum (in absence of overt affective comorbidity) that may impair remission in PD.