# Insomnia Severity Index Score: What It Means

What the Insomnia Severity Index (ISI) measures, what each score band from 0 to 28 means, the cutoff of 10, and what to do with your result.

Source: https://cpapclarity.com/learn/insomnia-severity-index-guide
Published: 2026-04-06
Updated: 2026-10-11
Author: Brian C.

Informational, not medical advice. Talk to your sleep physician before changing your therapy, pressure, mask, or medications.

## What Is the Insomnia Severity Index?

The Insomnia Severity Index (ISI) is a seven-question insomnia questionnaire scored from 0 to 28. Its authors interpret 0 to 7 as absence of insomnia, 8 to 14 as sub-threshold insomnia, 15 to 21 as moderate insomnia and 22 to 28 as severe insomnia, and a community study found 10 or more the best single cutoff for finding people with insomnia (Morin et al., 2011). If you have a total, [our ISI score page](https://cpapclarity.com/tools/insomnia-severity-index) shows its band.

The ISI was developed by Charles Morin and colleagues at Université Laval in Quebec. Bastien, Vallières and Morin validated it as a research outcome measure in *Sleep Medicine* in 2001, and Morin and colleagues published its case-finding cutoffs in *Sleep* in 2011 ([full paper on PubMed Central](https://pmc.ncbi.nlm.nih.gov/articles/PMC3079939/)). Sleep specialists use it both to screen and to track whether treatment is working, because it is short enough to repeat at every visit.

The ISI is copyrighted by Dr. Morin and distributed under license by Mapi Research Trust. CPAP Clarity does not reprint it. Your doctor, therapist or sleep clinic can give you the official version, and our score page explains the total. If you want a free insomnia questionnaire you can take right here, the [Sleep Condition Indicator](https://cpapclarity.com/tools/sleep-condition-indicator) is licensed for free non-commercial use; our [SCI guide](https://cpapclarity.com/learn/sleep-condition-indicator-guide) explains it.

## What the ISI Covers

The seven questions ask about the recent past. In plain terms, they cover how hard it has been to fall asleep, to stay asleep and not to wake too early, how satisfied you are with your sleep, how noticeable the problem is to other people, how much it worries you, and how much it gets in the way of your daytime life. Each is scored from 0 to 4, and the seven scores are added for a total from 0 to 28.

Three of the questions are about sleep itself and four are about its impact. That mix is deliberate: insomnia disorder is defined by both the night-time difficulty and the distress or impairment it causes.

## What Each Score Band Means

Morin and colleagues give this interpretation of the total:

- **0 to 7: absence of insomnia.** Occasional bad nights happen to everyone; this range does not suggest an insomnia problem.
- **8 to 14: sub-threshold insomnia.** Some symptoms, below the level the authors class as clinical. In their community sample, a total of 10 or more was the best single cutoff for finding people with insomnia (86.1% sensitivity, 87.7% specificity), so a total from 10 to 14 is worth mentioning to your doctor, especially if it bothers you.
- **15 to 21: moderate insomnia.** Worth discussing with your doctor.
- **22 to 28: severe insomnia.** Worth discussing with your doctor, particularly if it is affecting your work, mood or safety.

These bands describe how severe the symptoms are. They do not diagnose insomnia disorder, which a clinician confirms from your history, and they do not identify a cause. Pain, medications, mood, and other sleep disorders, including sleep apnea, can all drive the same score.

## Tracking a Change

The ISI was built to measure change. In the 2011 study, a drop of about **8.4 points** went with moderate improvement after treatment, as judged by an independent assessor who did not know which treatment people had. A total below 8 after treatment falls back into the range the authors call absence of insomnia.

If you are in treatment, keep each total with the date you took it. Our score page lets you enter an earlier total next to the current one and shows the change.

## Why Insomnia Matters for CPAP Users

Insomnia and obstructive sleep apnea often occur together. A 2019 meta-analysis of 37 studies by Zhang and colleagues in *Sleep Medicine Reviews* found that **38%** of people with obstructive sleep apnea met criteria for insomnia ([abstract on PubMed](https://pubmed.ncbi.nlm.nih.gov/30844624/)). A 2019 review by Sweetman, Lack and Bastien in *Brain Sciences* noted that insomnia symptoms tend to lower CPAP use ([review on PubMed Central](https://pmc.ncbi.nlm.nih.gov/articles/PMC6956217/)). Researchers call the combination COMISA, comorbid insomnia and sleep apnea.

The practical point: CPAP treats the airway. It does not treat the racing thoughts or conditioned wakefulness behind insomnia. If your CPAP data shows a well-controlled AHI but you still sleep badly, insomnia is one possible reason to raise with your doctor. Our guide to being [still tired on CPAP](https://cpapclarity.com/learn/still-tired-on-cpap) walks through the others, and you can [analyze your CPAP data](https://cpapclarity.com/) to see whether short or broken nights line up with how you feel.

## Treatment Your Doctor May Discuss

The American College of Physicians recommends cognitive behavioral therapy for insomnia (CBT-I) as the first treatment for chronic insomnia disorder in adults ([Qaseem et al., 2016, *Annals of Internal Medicine*](https://pubmed.ncbi.nlm.nih.gov/27136449/)). CBT-I is a structured program that works on sleep habits, time in bed and the worry that keeps people awake. It is offered by trained therapists and through some digital programs. Medication is a separate decision the same guideline leaves to a shared conversation with your doctor.

Keeping a regular wake time, keeping the bedroom dark and cool, and avoiding screens late at night are reasonable habits at any score, but they are not a substitute for treatment when the score is in the moderate or severe range.

## When to Talk to Your Doctor

Talk to your doctor if your total is 15 or more, if it is 10 or more and the problem bothers you, if poor sleep has lasted for months, or if you have fallen asleep at the wheel or nearly so. Bring your total and the date, and mention if you use CPAP. Quantified sleep complaints are easier for a provider to act on than a vague "I'm not sleeping well."

## Frequently Asked Questions

### What is a normal Insomnia Severity Index score?

A total of 0 to 7 is the range the ISI's authors describe as absence of insomnia. A total of 8 to 14 is sub-threshold insomnia, 15 to 21 is moderate and 22 to 28 is severe.

### What ISI score suggests insomnia?

In a community study by Morin and colleagues, a total of 10 or more was the best single cutoff for finding people with insomnia, with 86.1% sensitivity and 87.7% specificity. A total of 15 or more is the moderate range.

### Can I take the Insomnia Severity Index on CPAP Clarity?

No. The ISI is licensed through Mapi Research Trust, so we explain scores but do not reprint it. Ask your doctor for the official version, or take the free Sleep Condition Indicator on this site.

### How much does an ISI score need to drop to show improvement?

In the 2011 validation study, a drop of about 8.4 points went with moderate improvement after treatment. A total below 8 after treatment is in the range the authors call absence of insomnia.

## Primary Sources

- 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. [PubMed](https://pubmed.ncbi.nlm.nih.gov/11438246/)
- 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. [PubMed Central](https://pmc.ncbi.nlm.nih.gov/articles/PMC3079939/)
- Zhang Y, Ren R, Lei F, et al. Worldwide and regional prevalence rates of co-occurrence of insomnia and insomnia symptoms with obstructive sleep apnea: a systematic review and meta-analysis. *Sleep Med Rev*. 2019;45:1-17. [PubMed](https://pubmed.ncbi.nlm.nih.gov/30844624/)
- Sweetman A, Lack L, Bastien C. Co-Morbid Insomnia and Sleep Apnea (COMISA): Prevalence, Consequences, Methodological Considerations, and Recent Randomized Controlled Trials. *Brain Sci*. 2019;9(12):371. [PubMed Central](https://pmc.ncbi.nlm.nih.gov/articles/PMC6956217/)
- Qaseem A, Kansagara D, Forciea MA, Cooke M, Denberg TD. Management of Chronic Insomnia Disorder in Adults: A Clinical Practice Guideline From the American College of Physicians. *Ann Intern Med*. 2016;165(2):125-133. [PubMed](https://pubmed.ncbi.nlm.nih.gov/27136449/)