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Pittsburgh Sleep Quality Index

PSQI
health sciencespsychologyFree for research use

Permission: Free for research use. Free for non-commercial academic research, with no licence fee. Cite the original publication.

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.

Citing this in a methods section? This scale spans more than one discipline, so the style depends on where you publish. See the APA 7 or Vancouver guides, or compare all six citation styles.

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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.