Analysis

The Pittsburgh Sleep Quality Index (PSQI) is a standardized self-report questionnaire used to assess sleep quality over the past month. It was developed by Dr. D.J. Buysse, C.F. Reynolds, T.H. Monk, S.R. Berman, and D.J. Kupfer in 1989.

Objective

The PSQI measures various aspects of sleep during the past month and helps in identifying sleep disorders and problems related to sleep quality.

Question Scoring

The PSQI consists of 19 items distributed across seven clinically distinct components of sleep difficulties, which are:
Subjective Sleep Quality
Sleep Latency
Sleep Duration
Sleep Efficiency
Sleep Disturbances
Use of Sleeping Medications
Daytime Dysfunction
Responses for each subscale are rated on a 4-point Likert scale, ranging from 0 (no difficulty/best condition) to 3 (severe difficulty/worst condition).

Statistical Analysis

The global PSQI score is derived from the sum of the seven component scores and ranges from 0 (high sleep quality) to 21 (poor sleep quality). A total score of 5 or greater is indicative of poor sleep quality, with higher scores reflecting greater impairment.

Validity and Reliability

The PSQI was developed based on a theoretical understanding of sleep quality and comprehensively addresses its core dimensions. Factor analyses have shown that the PSQI subscales clearly reflect the theoretical constructs of sleep quality. The Cronbach’s alpha for the PSQI subscales typically exceeds 0.70, indicating acceptable internal consistency.

References

Buysse, D.J., Reynolds, C.F., Monk, T.H., Berman, S.R., & Kupfer, D.J. (1989). The Pittsburgh Sleep Quality Index (PSQI): A new instrument for psychiatric research and practice. Psychiatry Research, 28(2), 193–213.