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Pittsburgh Sleep Quality Index

PSQI
health sciencespsychologyFree for research use

A 19-item self-report questionnaire assessing sleep quality and disturbances over the past month, yielding seven component scores and a global score.

Items
19
Response format
Mixed open-ended and 4-point (0-3) items across 7 components
Version
1.0
Subscales
7

Ready-to-cite methods sentence

Sleep quality was assessed with the Pittsburgh Sleep Quality Index (PSQI; Buysse et al., 1989), whose global score (0-21) had good internal consistency (α ≈ .83); a global score above 5 indicates poor sleep quality.

Reliability & validation

Validation population
Healthy adults and clinical samples (Buysse et al., 1989)
Cronbach's α
0.83

Subscales

Sleep qualitySleep latencySleep durationSleep efficiencySleep disturbancesUse of sleep medicationDaytime dysfunction

Known limitations

Free for non-commercial research use. Retrospective self-report over a month; the composite global score can obscure which specific sleep components are affected.

Original citation

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

https://doi.org/10.1016/0165-1781(89)90047-4

Questions researchers ask

What does the PSQI measure?

A 19-item self-report questionnaire assessing sleep quality and disturbances over the past month, yielding seven component scores and a global score.

How many items does the PSQI have?

The Pittsburgh Sleep Quality Index (PSQI) has 19 items across 7 subscales: Sleep quality, Sleep latency, Sleep duration, Sleep efficiency, Sleep disturbances, Use of sleep medication, Daytime dysfunction.

Is the PSQI free to use?

The PSQI is free to use for non-commercial academic research. You don't need to pay a license fee, but you should always cite the original publication.

Is the PSQI reliable?

Validation studies report Cronbach's α of 0.83. See the reliability section for the population studied and full statistics.

Who developed the PSQI, and how do I cite it?

Buysse, D. J., Reynolds, C. F., Monk, T. H., Berman, S. R., Kupfer, D. J. (1989). The Pittsburgh Sleep Quality Index: A new instrument for psychiatric practice and research. Psychiatry Research, 28(2), 193-213. https://doi.org/10.1016/0165-1781(89)90047-4

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Library entry verified July 2026. Metadata is provided for reference; item wording is available inside Folio Surveyor, subject to each instrument's licensing.