The Pittsburgh Sleep Quality Index (PSQI) is the most widely used self-report measure of global sleep quality. It covers the past month through 19 self-rated items (plus five bed-partner items that are not scored), which combine into seven component scores - subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction - each scored 0-3.
The seven components sum to a global score of 0-21, with higher scores indicating worse sleep quality. A global score above 5 distinguishes "poor sleepers" from "good sleepers". Because it aggregates quantity, quality and daytime consequences into one index, it characterises overall sleep health rather than any single sleep disorder.
02 - Origin & purpose
Where it comes from.
The PSQI was developed by Daniel Buysse and colleagues at the University of Pittsburgh, with NIMH funding, and published in Psychiatry Research in 1989. It was designed for psychiatric practice and research, where sleep disturbance is both a symptom and a risk factor across most diagnoses.
It has since become the de facto standard for quantifying sleep quality in clinical research across medicine, translated and validated in dozens of languages. A brief six-item version (B-PSQI) was published by the Pittsburgh group in 2021 under the same copyright.
03 - Scoring & cutoffs
How scoring works.
Scoring is not a simple sum of items: responses are first mapped onto the seven components (each 0-3) using the published scoring algorithm, and the components are then summed to the 0-21 global score.
The validated cutoff is a global score greater than 5, which in the original validation distinguished poor from good sleepers with sensitivity 89.6% and specificity 86.5% (kappa = 0.75). Because component scoring is rule-based and easy to get wrong by hand, scoring software or the official instructions should be used.
Score
Severity
Interpretation
0–5
Good sleep quality
Below the clinical cutoff.
6–21
Poor sleep quality
Above the validated >5 cutoff. Higher scores indicate greater severity, but bands within this range are not formally validated.
04 - Validation evidence
How well it performs.
In the original validation across clinical and control samples, a global score above 5 yielded sensitivity 89.6% and specificity 86.5% against clinical diagnosis (Buysse et al., 1989). Internal consistency for the global score was good (Cronbach's alpha = 0.83) and test-retest reliability high (r = 0.85).
A 2016 COSMIN-based systematic review and meta-analysis of 37 studies found good internal consistency and strong evidence for reliability and validity across clinical and non-clinical samples, with moderate evidence for structural validity (Mollayeva et al., 2016).
89.6%
SENSITIVITY (>5)
Global score above 5 vs clinical diagnosis (Buysse et al., 1989)
86.5%
SPECIFICITY (>5)
Global score above 5 vs clinical diagnosis (Buysse et al., 1989)
0.83
CRONBACH'S α
Internal consistency, global score
0.85
TEST–RETEST r
Stability of the global score
05 - How it compares
How it compares to the alternatives.
Instrument
Items
Time
When to reach for it
PSQI
19
~5–10 min
Global sleep quality over the past month across seven components. Licensed by the University of Pittsburgh.
Daytime sleepiness propensity, not sleep quality. Licensed.
STOP-BANG
8
~2 min
Obstructive sleep apnoea risk. Reach for it when snoring, witnessed apnoeas or resistant hypertension raise suspicion.
B-PSQI
6
~2 min
Brief version of the PSQI, under the same University of Pittsburgh copyright.
Sleep diary
daily
1–2 weeks
Prospective night-by-night data; the better tool for nightly variability and behavioural treatment.
06 - When to use it
Right tool, wrong tool.
In the comparison above, instruments without a page link are not yet in the Aisel library.
The PSQI is best read as a summary of sleep health over the past month, not as a diagnosis of any one sleep disorder.
Reach for it when
-Characterising overall sleep health over the past month in psychiatric assessment.
-Research where a single validated global index of sleep quality is needed.
-Mixed or unclear sleep complaints, before narrowing to a specific disorder.
-Non-commercial clinical and academic settings covered by the free licence.
Reach for something else when
-Monitoring insomnia treatment response - the ISI is more change-sensitive.
-Suspected sleep apnoea - use STOP-BANG, then objective testing.
-Night-by-night variability - use a prospective sleep diary.
-Any commercial deployment without a licence from the University of Pittsburgh.
07 - Confidence & precision
Reading the score with care.
Test-retest reliability of the global score is high (r = 0.85), and agreement with clinical diagnosis at the cutoff above 5 was strong in the original validation (kappa = 0.75). No universally accepted minimal clinically important difference has been established for the global score, so small changes should be interpreted cautiously.
The same global score can also arise from different component profiles - two patients scoring 8 may have entirely different problems - so the component scores deserve a look before the total is interpreted.
08 - Limitations
What it cannot tell you.
Its factor structure is debated: systematic reviews find single-factor, two-factor and three-factor solutions across populations, so the single global score can mask a multidimensional picture. Self-reported sleep also diverges from objective measurement by actigraphy or polysomnography, particularly for sleep duration and latency.
The rule-based component scoring invites hand-scoring errors, and one-month retrospective recall is vulnerable to bias. The copyright limits use as well: the PSQI is free for non-commercial research, education and individual clinical practice, but commercial use requires a licence - which is why this page explains the instrument rather than hosting it.
09 - Licensing, explained
How licensing works.
The PSQI is copyrighted by the University of Pittsburgh. It may be reproduced without charge only for non-commercial research and educational purposes, and clinicians may use it in their own practice; any commercial use requires a licence from the University of Pittsburgh's Innovation Institute.
Aisel therefore cannot host the questionnaire or a scorable version. Clinicians can obtain the instrument and scoring instructions from the University of Pittsburgh's Center for Sleep and Circadian Science.
For a scorable insomnia measure in this library, see the ISI.
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