Interactive Interpreter

ISI: Insomnia Severity Index

The ISI (Insomnia Severity Index) is a 7-item self-report questionnaire that measures the perceived severity of insomnia symptoms over the past two weeks. Total scores range from 0 to 28 across four severity bands, and it is a primary outcome measure in CBT-I trials.

For professional reference, research, and education only. Not for diagnosis or medical advice.

ISI Score Interpreter

  • ISI Score Calculator

    Enter each of the 7 items (0–4) to total them and see the band. Items are numbered, not reproduced — enter them from the form in front of you. Scoring aid only; it does not diagnose.

    0 of 7 items entered — 7 still blank. The total can only rise, so treat the range as provisional.

    Item 1
    Item 2
    Item 3
    Item 4
    Item 5
    Item 6
    Item 7

    Each item scores 0–4. Response anchors differ by item on this scale, so use the wording printed on the form.

  • Enter a total score to see its range.

  • 7 items, each rated 0–4; total score 0–28. Higher scores indicate greater insomnia severity.

    Total scoreInterpretation
    22+Severe clinical insomniaScore indicates severe insomnia warranting prompt clinical evaluation and evidence-based treatment such as CBT-I.
    15–21Moderate clinical insomniaScore indicates clinical insomnia of moderate severity; further assessment and treatment planning are recommended.
    8–14Subthreshold insomniaScore suggests subthreshold insomnia; symptoms may warrant monitoring and preventive intervention.
    0–7No clinically significant insomniaScore in the range associated with no clinically significant insomnia in validation samples.

    Bastien et al. (2001); Morin et al. (2011). Severity bands per published validation studies.

The ISI (Insomnia Severity Index) is a 7-item self-report questionnaire that measures how severe a person's insomnia has felt over the past two weeks, scored 0 to 28. It is used both to screen for insomnia and as an outcome measure in treatment research [2].

What does the ISI measure?

The ISI covers sleep-onset difficulty, sleep-maintenance difficulty, early morning awakenings, sleep dissatisfaction, interference with daily functioning, how noticeable the problem is to others, and distress about sleep. It was first published in Morin's 1993 book Insomnia: Psychological assessment and management, and its first psychometric validation found adequate internal consistency and sensitivity to change with treatment [2].

The total maps to four severity categories. The ISI is used to detect insomnia cases in the community and in primary care [1] [3], and to track response to treatment such as cognitive behavioural therapy for insomnia (CBT-I), an adaptation of CBT.

How do you give the ISI?

The ISI is completed by the client.

Instructions: Rate each of the following over the past 2 weeks.

All items use a 0–4 scale where 0 = None / Not at all and 4 = Very Severe / Very Much.

Severity of insomnia problems

How severe have your insomnia symptoms been in the past 2 weeks?

Sleep satisfaction

How satisfied / dissatisfied are you with your current sleep pattern?

Daily functioning

To what extent do you consider your sleep problem to interfere with your daily functioning (e.g., daytime fatigue, concentration, work performance, mood)?

Impact on quality of life

How noticeable to others do you think your sleeping problem is in terms of impairing the quality of your life?

Worry / distress

How worried / distressed are you about your current sleep problem?

How do you score and interpret the ISI?

Each item is rated on a 0–4 Likert scale and all items are summed; total scores range from 0 to 28. No items are reverse-scored. The ISI classifies insomnia into four categories: 0–7 (no clinically significant insomnia), 8–14 (subthreshold insomnia), 15–21 (clinical insomnia, moderate severity), and 22–28 (clinical insomnia, severe).

ISI item structure

  • Items 1–3: difficulty falling asleep, staying asleep, and waking too early (0 = none to 4 = very severe each).
  • Item 4: satisfaction with the current sleep pattern (0 = very satisfied to 4 = very dissatisfied).
  • Item 5: how much the sleep problem interferes with daily functioning (0 = not at all to 4 = very much).
  • Item 6: how noticeable the sleep problem is to others in terms of quality of life.
  • Item 7: worry or distress about the sleep problem (0 = not at all to 4 = very much).

Documenting ISI results

The ISI total score and severity range belong in the Objective section of a SOAP note.

Psychometric properties

  • Internal consistency: Cronbach's alpha of 0.90 and 0.91 in community and clinical samples [1] and 0.92 in primary care [3].
  • Case detection in the community: a cutoff of 10 was optimal (86.1% sensitivity, 87.7% specificity) [1].
  • Case detection in primary care: a cutoff of 14 was optimal (82.4% sensitivity, 82.1% specificity; AUC 0.87) [3].
  • Treatment response: in a clinical sample, a change of -8.4 points was associated with moderate improvement rated by an independent assessor [1].
  • Informant convergence: scores from the self-report version converge closely with clinician and significant-other versions [2].
  • Outcome measure: the ISI detected changes in perceived sleep difficulties with treatment in a randomized trial of behavioural and medication treatments in older adults [2].

Limitations

  • Screening, not diagnosis. A high ISI score warrants clinical evaluation; it does not constitute a diagnosis. Diagnosis requires a clinical interview that considers duration, frequency, daytime impairment, and exclusion of other causes.
  • Perceived severity. The ISI captures the client's perception of sleep difficulty, not objective sleep measured by diaries or polysomnography.
  • Cutoffs vary by setting. The optimal case-detection cutoff differed between community (10) and primary care (14) samples [1] [3].

How does insomnia relate to other mental health conditions?

Insomnia often occurs alongside depression, anxiety and PTSD. Scores on the ISI correlated with anxiety and depression measures in its validation [1], and in PTSD, sleep disturbance is one of the diagnostic criteria. See also major depressive disorder.

When giving the ISI alongside mood or anxiety measures such as the PHQ-9 and GAD-7, document whether sleep difficulties are primary or secondary to guide treatment sequencing.

For individuals: This page is a clinical reference, not a diagnostic tool. If you have concerns about your own symptoms, bring this information to a qualified mental health professional.

Related

FAQ

  • How is the ISI scored?

    The ISI contains 7 items, each rated on a 0–4 Likert scale. All item scores are summed to produce a total between 0 and 28. No items are reverse-scored.

  • What do ISI score ranges mean?

    Scores of 0–7 indicate no clinically significant insomnia, 8–14 subthreshold insomnia, 15–21 moderate clinical insomnia, and 22–28 severe clinical insomnia. These are the published ISI severity categories.

  • Is the ISI self-report or clinician-administered?

    The ISI is a self-report questionnaire completed by the person whose sleep is being rated. Clinician and significant-other versions have also been studied, and their scores converge closely with the self-report version.

  • Can the ISI diagnose insomnia disorder?

    No. The ISI is a screening and outcome measure, not a diagnostic tool. A high score warrants clinical follow-up; diagnosis requires a clinical interview that considers duration, frequency, daytime impairment, and exclusion of other causes.

References

    1. 1.Morin CM, Belleville G, Bélanger L, Ivers H. The Insomnia Severity Index: psychometric indicators to detect insomnia cases and evaluate treatment response. Sleep. 2011;34(5):601-608.
    2. 2.Bastien CH, Vallières A, Morin CM. Validation of the Insomnia Severity Index as an outcome measure for insomnia research. Sleep Med. 2001;2(4):297-307.
    3. 3.Gagnon C, Bélanger L, Ivers H, Morin CM. Validation of the Insomnia Severity Index in primary care. J Am Board Fam Med. 2013;26(6):701-10.

    ISI © Charles M. Morin. Distributed by Mapi Research Trust (ePROVIDE); licensing terms apply and vary by user type (academic, clinical or commercial).

HiBoop does not offer this scale. This page is reference material.This library is an academic and clinical reference. A scale described here is not necessarily offered in HiBoop; each page says whether it is.

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