• Sleep
  • General medicine
  • Mental health

ISI score

Assess the severity of insomnia

The Insomnia Severity Index (ISI) assesses the perceived severity of insomnia difficulties and their impact. This self-administered questionnaire complements the initial interview and can help measure progress during management. It is not sufficient on its own to diagnose chronic insomnia.

Number of questions
7 questions
Approximate duration
2 to 3 minutes
Population
Adults
Modality
Self-administered questionnaire

QuestionnaireISI

SELF-QUESTIONNAIRE

The items assess nighttime difficulties (falling asleep, staying asleep, waking up early) as well as the associated dissatisfaction, impact, noticeable effects to others, and distress. Each response is scored from 0 to 4.

Are you patient?

You can complete the ISI yourself, taking into account the entire specified period. The professional will put the result into context with the history of your sleep difficulties.

Terms of contract

The recall window must remain visible. Some forms use different time periods: a longitudinal comparison requires keeping the same version. Measurements taken too close together may cover almost the same nights.

Score interpretationISI

The total score is the sum of the seven items (1a + 1b + 1c + 2 + 3 + 4 + 5), ranging from 0 to 28.

Total score

First reading

  • 0 to 7

    No clinically significant complaint of insomnia (0 to 7).

  • 8 to 14

    Complaints of sub-clinical insomnia, of mild severity (8 to 14).

  • 15 to 21

    Complaints of clinically significant insomnia of moderate severity (15 to 21).

  • 22 to 28

    Complaints of severe insomnia (22 to 28).

0 to 7: no clinically significant insomnia; 8 to 14: sub-threshold (mild) insomnia; 15 to 21: clinically significant (moderate) insomnia; 22 to 28: severe insomnia. Population screening thresholds do not necessarily correspond to this classification.

The ISI is self-reported: it does not directly measure sleep duration and does not, on its own, characterise the chronicity, aetiology, or comorbidities of insomnia. The categories replace neither the analysis of the disorder's duration nor the investigation of associated factors.

Frequently asked questions

Sources and references

Charles M. Morin et al.

ISI Form, C. Morin (1993). Psychometric validation: Sleep, 2011.

Questionnaires and associated scores

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