Test-retest reliability and validity of the Pittsburgh Sleep Quality Index in primary insomnia

Objective: Psychometric evaluation of the Pittsburgh Sleep Quality Index (PSQI) for primary insomnia. Methods: The study sample consisted of 80 patients with primary insomnia (DSM-IV). The length of the test-retest interval was either 2 days or several weeks. Validity analyses were calculated for PSQI data and data from sleep diaries, as well as polysomnography. To evaluate the specificity of the PSQI, insomnia patients were compared with a control group of 45 healthy subjects. Results: In primary insomnia patients, the overall PSQI global score correlation coefficient for test-retest reliability was .87. Validity analyses showed high correlations between PSQI and sleep log data and lower correlations with polysomnography data. A PSQI global score > 5 resulted in a sensitivity of 98.7 and specificity of 84.8 as a marker for sleep disturbances in insomnia patients versus controls. Conclusion: The PSQI has a high test-retest reliability and a good validity for patients with primary insomnia.