to an increased risk of suicide compared with those without NP.
11However, these comparisons were mainly made on patients with DP/NP and those with primary DP. Meanwhile, one study that included both primary NP and DP/NP demonstrated no differences between NP and primary DP in terms of frequency of comorbid depression.12 Thus, the clinical signifi cance of primary NP as well as that of DP/NP remains unclear, although it is possible that the latter is a severe subcategory of PD.This study set out to compare clinical characteristics including demographic variables, panic symptom items, severity of Objective: Many patients with panic disorder (PD) experience nocturnal panic attacks. We investigated the differences in demographic variables and symptom characteristics as well as response to treatment among patients with primary day panic (DP), primary nocturnal panic (NP), and the coexistence of DP and NP (DP/NP), and discuss whether NP is a distinct disease category. Method: One hundred one consecutive untreated patients with PD were enrolled and subsequently divided into the NP, DP, and DP/NP groups. The presence of 13 panic attack symptom items as well as scores on the Panic Disorder Severity Scale (PDSS) and the Pittsburgh Sleep Quality Index (PSQI) were compared among the groups. After 3 months of regular treatment, PDSS scores were assessed again to evaluate treatment response. Results: Nocturnal panic attacks of the participants were mostly reported to occur in the fi rst tertile of nocturnal sleep. The number of males, onset age, and presence of choking sensation were signifi cantly higher, and the PDSS score was signifi cantly lower in the NP group compared with the other groups. The DP/NP group showed the highest PDSS score, and participants in this group were prescribed the highest doses of medication among all groups. Only diagnostic subcategory was signifi cantly associated with treatment response. The total score for PDSS and PSQI correlated signifi cantly only in the NP group. Conclusions: DP/NP could be a severe form of PD, while primary NP could be a relatively mild subcategory that may partially share common pathophysiology with adult type night terror.
S C I E N T I f I C I N V E S T I g A T I O N SP anic disorder (PD) is an anxiety disorder characterized by recurrent daytime panic (DP) attacks (primary DP).1 However, some patients who fulfi ll the clinical criteria for PD experience panic attacks mainly during the nocturnal sleep period.
2-4These nighttime attacks occur without any obvious triggers during periods of sleep-wake transition and are referred to as nocturnal panic (NP) attacks. 5 In general, 18% to 45% of PD patients experience both DP and NP attacks (DP/NP).6,7 Meanwhile, there are a considerable number of patients who have panic attacks only during the nocturnal sleep period (primary NP). However, most previous reports have not mentioned the clinical characteristics of primary NP, except for one report in which the response to pharmaceutical treatment in such patients was discussed....