2.2.3. Pittsburgh Insomnia Rating Scale, 20-Item Version

The 20-item version of the Pittsburgh insomnia rating scale (PIRS-20) is a self-report questionnaire derived from the original 65-item PIRS. It has 12 items on nighttime and daytime distress symptoms; 4 items on sleep parameters; and 4 items on quality, regularity, and depth of sleep to assess the patient’s sleep condition in the preceding week [16,17]. Each item is scored on a 4-point scale from 0 (not at all bothered) to 3 (severely bothered), with total scores ranging from 0 to 60, to provide an index of insomnia severity; a cut-off score of 20 was used to determine whether the respondent had clinical insomnia [17]. The PIRS-20 has a Cronbach’s alpha of 0.95 and a test-retest reliability of 0.92 [18].