ISI
Insomnia Severity Index
A brief measure of insomnia severity and its daytime impact.
7
3 min
adult
0–28
About the ISI
The Insomnia Severity Index (ISI) is a seven-item self-report measure of the nature, severity, and impact of insomnia. It captures both night-time symptoms — difficulty falling asleep, staying asleep, and early waking — and the daytime consequences and distress that define clinically significant insomnia.
Items are rated on a 0–4 scale for a total of 0 to 28. Scores are grouped into no clinically significant insomnia, subthreshold, moderate, and severe insomnia, and the ISI is sensitive enough to track change across treatment such as CBT for insomnia.
What it measures
- Severity of sleep-onset, sleep-maintenance, and early-morning-waking problems
- Satisfaction with current sleep pattern
- Interference with daytime functioning and how noticeable the impairment is to others
- Distress or worry caused by the sleep problem
ISI questions
- 1
Severity of your insomnia problem: difficulty falling asleep
None · Mild · Moderate · Severe · Very severe - 2
Severity of your insomnia problem: difficulty staying asleep
None · Mild · Moderate · Severe · Very severe - 3
Severity of your insomnia problem: problem waking up too early
None · Mild · Moderate · Severe · Very severe - 4
How satisfied/dissatisfied are you with your current sleep pattern?
Very satisfied · Satisfied · Moderately satisfied · Dissatisfied · Very dissatisfied - 5
How noticeable to others do you think your sleep problem is in terms of impairing the quality of your life?
Not at all noticeable · A little · Somewhat · Much · Very much noticeable - 6
How worried/distressed are you about your current sleep problem?
Not at all worried · A little · Somewhat · Much · Very much worried - 7
To what extent do you consider your sleep problem to interfere with your daily functioning?
Not at all interfering · A little · Somewhat · Much · Very much interfering
Items reproduced from a documented, freely usable source. Item wording is preserved exactly as published.
Scoring & interpretation
| Range | Band | Interpretation |
|---|---|---|
| 0–7 | No insomnia | No clinically significant insomnia. |
| 8–14 | Subthreshold | Subthreshold insomnia; monitor. |
| 15–21 | Moderate | Clinical insomnia (moderate severity). |
| 22–28 | Severe | Clinical insomnia (severe). |
Higher scores indicate greater symptom severity.
Clinical applications
- Screening and severity grading of insomnia
- Outcome monitoring in CBT-I and sleep-medicine settings
Frequently asked questions
What is a high ISI score?
Totals of 0–7 indicate no clinically significant insomnia, 8–14 subthreshold, 15–21 moderate, and 22–28 severe insomnia.
Source & references
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