The PSQI sleep quality index: how to read the result
What the PSQI measures, its seven components, what the threshold of 5 means, and why this page explains the scale without reprinting the questionnaire.
Key points
- The PSQI combines 19 self-reported items into seven components, each scored 0 to 3, total 0 to 21. A higher score means worse sleep.
- The familiar threshold is 5: a total above 5 is regarded as "poor sleep quality".
- The PSQI asks about the LAST MONTH, unlike scales that ask about two weeks. That is why it reflects a settled sleep pattern rather than an acute bout of insomnia.
- The PSQI measures sleep quality in general. It does NOT diagnose insomnia and does not distinguish between causes. A high score from sleep apnoea and a high score from psychophysiological insomnia look the same.
The PSQI measures seven things, not one
Most readers imagine a "sleep quality index" as one number about whether sleep was good or bad. The PSQI instead divides sleep into seven separate aspects, scores each, and only then adds them up. That division is the value of the scale: two people with the same total of 10 may have entirely different problems.
| Component | What it asks about | Why this aspect matters on its own |
|---|---|---|
| Subjective sleep quality | How you rate your own sleep over the past month | Reflects the level of distress, a criterion that has to be present for a disorder |
| Sleep latency | How long after lying down you fall asleep | Over 30 minutes is the usual marker for trouble falling asleep |
| Sleep duration | How many hours you actually sleep each night | Short duration with daytime alertness is not an illness |
| Sleep efficiency | Hours asleep divided by hours in bed | This is the measure that sleep restriction therapy targets |
| Sleep disturbances | Awakenings, snoring, breathing difficulty, pain, night-time urination | This is where sleep apnoea and chronic pain show themselves |
| Use of sleep medication | How often medication is taken for sleep | Where medication is masking symptoms, the other aspects read falsely "good" |
| Daytime dysfunction | Daytime sleepiness, reduced enthusiasm for activity | Without this aspect, the criteria for insomnia disorder are not met |
What a threshold of 5 means, and what it does not
A total above 5 is regarded as poor sleep quality. The threshold separates normal sleepers from people with sleep problems reasonably well, which makes it useful for screening in a population. In Vietnam, a 2024 study of patients at Hue University of Medicine and Pharmacy Hospital found 60.7% scoring 5 or more. That figure shows the scale of the problem rather than showing that 60.7% of them need treatment.
Why this page does not print the questionnaire
The PSQI is a copyrighted instrument. Many Vietnamese pages print the whole questionnaire, and most of them also print the scoring wrongly. The two Vietnamese PSQI pages we surveyed display only the text without scoring it, so readers answer everything and still do not know their score. PSQI scoring is not simple: the seven components each have their own formula, and sleep efficiency has to be calculated from bedtime, wake time and actual hours slept. A page that prints the questionnaire without scoring it correctly is worse than one that does not print it.
If you want a result right now, use the clinic's own insomnia screen. We wrote that one from the diagnostic criteria, so it can be printed and scored publicly. If you want the PSQI itself, it forms part of the history taken during a consultation.
About the copyright of this questionnaire
The PSQI (Pittsburgh Sleep Quality Index) was published by Daniel J. Buysse and colleagues at the University of Pittsburgh in 1989. The scale is free ONLY for non-commercial research and educational use; clinical or commercial use requires an annual licence fee. A public website falls in the fee-paying group. This page therefore EXPLAINS the scale and how to read it, and does NOT reprint the questionnaire. The PSQI is the only sleep scale with published Vietnamese validation data, and the clinic uses that version during consultations.
Frequently asked questions
- How does the PSQI differ from the clinic's insomnia screen?
- The PSQI measures sleep quality over the past month across seven aspects and produces a score. The clinic's screen follows the diagnostic criteria: it checks whether you have night-time symptoms, daytime consequences, enough frequency and enough duration all at once. One answers "how bad is the sleep", the other answers "is this an insomnia disorder".
- Does a high PSQI mean I should take sleeping pills?
- No. A high score only says sleep is poor. If the cause is sleep apnoea then sleeping pills make it worse, because they suppress the protective arousal reflex. The cause has to be found first.
References
- The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research - Psychiatry Research, 1989 · DOI 10.1016/0165-1781(89)90047-4
- The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research - Psychiatry Research, 1989 · DOI 10.1016/0165-1781(89)90047-4
- Sleep Medicine Instruments - terms of use for the PSQI - University of Pittsburgh Sleep Medicine Institute, 2026