**2.3 Data extraction**

*Psychopathology - An International and Interdisciplinary Perspective*

The preferred reporting items for systematic reviews and meta-analysis (PRISMA) checklist was used to design the study and to report results based on best

We conducted a literature review in these databases: PsycNet, MedLine, ProQuest, Web of Knowledge, Cochrane, and Psychology and Behavioral Sciences Collection. Search terms used in PsycNet were "panic disorder" OR "panic attack" OR panic AND sleep OR "sleep disorders" OR insomnia OR "nocturnal panic" OR "sleep deprivation." Search terms used in MedLine, Web of Knowledge, and Cochrane were panic OR "panic disorder" AND sleep OR "sleep initiation and maintenance disorders" OR dyssomnia OR "sleep deprivation." Publication date was

To retrieve gray literature (i.e., unpublished work or studies that are published outside widely available journals) [43], reference lists of selected articles were searched for potentially eligible articles regarding sleep in PD. The Laval University library was searched for book chapters addressing sleep in PD. Reference lists were screened for articles of interest. Inclusion of ProQuest and Web of Knowledge databases helped retrieve gray literature, as these sources contain theses, symposia,

The following inclusion criteria were used: (a) studies had to be published in English, French, or Spanish; (b) minimum participant age was 18 years; (c) to ensure population representativeness, studies including participants with comorbidities were accepted if PD was the primary diagnosis for at least one subgroup; (d) studies had to report quantitative group data for at least one sleep variable; (e) data on sleep disturbances had to include means, standard deviations, and group sizes for PD and control groups; (f) prevalence of NPA had to be reported in percentage or number of participants, and total sample size had to be included; (g) data had to be issued from self-report questionnaires, clinician-administered interviews, sleep diaries, polysomnography, or actigraphy; and (h) for subjective and objective sleep data, patients with PD had to be compared to a group of healthy controls (for the prevalence of nocturnal panic, no comparison group was

Studies that met the following criterion were excluded: (a) studies in which all patients with PD reported a physical disease or one of the following comorbid psychiatric disorders, schizophrenia, bipolar disorder, and alcohol or drug abuse or dependence, and (b) studies in which no data could be grouped using the following

Studies were classified and grouped on the basis of the measure they reported. For example, all studies reporting results on the Pittsburgh sleep quality index (PSQI) were grouped together, the same was done for the Hamilton rating scale (HAM-D), polysomnography, etc. For articles reporting NPA, grouping was carried out on the basis of the frequency criteria used. For example, all studies reporting the prevalence of patients who had at least one NPA in their lifetime were grouped together, all articles reporting the prevalence of patients having at least one NPA/month were grouped together, etc. Some articles reported data from specific sleep measures or NPA frequency criteria that were not repeated elsewhere.

practices in the field of literature reviews and meta-analyses [42].

1980 (DSM-III year of publication) to May 2016 inclusive.

and convention papers, in addition to journal articles.

**2. Method**

**2.1 Literature research**

**2.2 Article selection**

necessary).

procedure:

**98**

Once reference retrieval was complete, each of the selected papers was reviewed, and data was extracted using a standardized rating form and coding manual. Extracted variables included information about the sample and sampling method, general methodology, and sleep characteristics (self-report sleep data, polysomnographic/actigraphic data, and prevalence of NPA).
