ISI · Insomnia
Do I have insomnia? Free Insomnia Severity Index (ISI) test
Sleep & Insomnia Self-Test
The Insomnia Severity Index - a free sleep problems self-test.
Reviewed by Komel Kaur, Psychotherapist
Last reviewed 9 July 2026
7
Questions
~2
Minutes
Free
Always
What the ISI measures
The ISI (Insomnia Severity Index) measures how severe your sleep problem has been over the past two weeks. Its 7 items cover difficulty falling asleep, staying asleep, and waking too early, satisfaction with your current sleep pattern, how noticeable the sleep problem feels to others, how distressed you are by it, and how much it interferes with daily functioning.
Each item is scored 0-4, giving a total between 0 and 28. Higher scores indicate more severe insomnia and greater impact on daytime functioning.
Because the ISI captures not only sleep symptoms but also distress and daytime impairment, it aligns closely with the diagnostic criteria for insomnia disorder rather than only measuring hours of sleep lost.
Where the ISI came from
The ISI was developed by Charles Morin at Université Laval in Quebec in the 1990s and revised through subsequent work by Bastien, Vallières, and Morin published in Sleep Medicine in 2001. It was designed to be brief, sensitive to change with treatment, and aligned with the diagnostic criteria for insomnia. It is now the standard patient-reported outcome measure in insomnia clinical trials worldwide and is recommended by the American Academy of Sleep Medicine as an outcome measure for cognitive behavioural therapy for insomnia (CBT-I).
How the ISI is scored
The ISI total maps to four severity bands. Scores of 15 or higher meet the threshold for clinical insomnia.
| Score | Severity | What it usually means |
|---|---|---|
| 0-7 | No clinically significant insomnia | Sleep is within the normal range. Sleep hygiene basics maintain this. |
| 8-14 | Subthreshold insomnia | Symptoms present but below the clinical threshold. Worth tightening sleep hygiene and monitoring. |
| 15-21 | Clinical insomnia (moderate) | Meets criteria for insomnia disorder. CBT-I is the recommended first-line treatment. |
| 22-28 | Clinical insomnia (severe) | Severe insomnia. Prompt evaluation and structured CBT-I with medical review recommended. |
How the ISI is used in clinical practice
The ISI is the standard measure used at intake in sleep clinics and to track change during CBT-I. A drop of 6 points or more is considered clinically meaningful; a post-treatment score below 8 is often used as a remission criterion.
It is used to differentiate insomnia from other sleep disorders. High ISI scores in the absence of daytime sleepiness point towards insomnia; high daytime sleepiness with normal-ish ISI points elsewhere (e.g., sleep apnoea).
It is also used in primary care to decide when to refer for CBT-I versus when sleep hygiene alone is likely to suffice.
Limitations to keep in mind
- ·The ISI is a self-report screen, not a diagnosis. Insomnia disorder is diagnosed via clinical interview and can require polysomnography to rule out other sleep pathology.
- ·It does not identify the cause of insomnia. Insomnia can be primary, or secondary to depression, anxiety, pain, medication, substance use, sleep apnoea, restless legs, or shift work.
- ·It measures the past two weeks. Long-term chronic insomnia is diagnosed only if symptoms have persisted for at least three months.
- ·It captures subjective sleep. Some people underestimate how much they sleep (paradoxical insomnia); others overestimate. Objective measures like actigraphy can complement the ISI when this is suspected.
Before you start
- · Find a quiet few minutes - answer honestly, not how you wish you felt.
- · There are no right or wrong answers. Pick what feels closest.
- · This is a screening tool, not a diagnosis.
- · If anything brings up something heavy, support is at the end.
Common questions about the ISI
What is the ISI?
The Insomnia Severity Index is a 7-item self-report measure of insomnia severity. It is the most widely used patient-reported outcome measure in insomnia research and treatment.
What is a normal ISI score?
Scores of 0-7 are considered no clinically significant insomnia. Scores of 8-14 are subthreshold, 15-21 moderate clinical insomnia, and 22-28 severe clinical insomnia.
Does the ISI diagnose insomnia disorder?
No. The ISI is a screen and severity measure. Insomnia disorder is diagnosed via clinical interview, taking into account duration, daytime impact, and rule-out of other sleep disorders.
What is the best treatment for a high ISI score?
Cognitive behavioural therapy for insomnia (CBT-I) is the recommended first-line treatment for chronic insomnia and outperforms sleep medication in the long term. Medication may be used short-term or when CBT-I is not available.
How often should I retake the ISI?
In CBT-I treatment it is typically repeated every 2-4 weeks to track progress. For personal use, every few weeks is reasonable.
Is the ISI free?
The ISI is copyrighted but is freely available for non-commercial clinical and research use.
Reviewed by Komel Kaur, Psychotherapist
Last reviewed 9 July 2026
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.