Insomnia Severity Index (ISI)
A 7-item scale assessing the severity of sleep-onset and sleep-maintenance difficulties over the past two weeks.
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Introduction
The Insomnia Severity Index (ISI) is a 7-item self-report instrument developed by Charles Morin to assess the severity of insomnia symptoms, satisfaction with sleep, and the impact of sleep problems on daily functioning over the past two weeks.
The total score ranges from 0 to 28. Scores of 15 and above indicate clinically significant insomnia and warrant professional consultation.
References
- Bastien, C. H., Vallières, A., & Morin, C. M. (2001). Validation of the Insomnia Severity Index as an outcome measure for insomnia research. Sleep Medicine, 2(4), 297-307. 10.1016/S1389-9457(00)00065-1
- Morin, C. M. (1993). Insomnia: Psychological assessment and management. Guilford Press.
- Morin, C. M., Belleville, G., Bélanger, L., & Ivers, H. (2011). The Insomnia Severity Index: Psychometric indicators to detect insomnia cases and evaluate treatment response. Sleep, 34(5), 601-608. 10.1093/sleep/34.5.601
Frequently Asked Questions
Have another question? Let us know.
What is the Insomnia Severity Index (ISI)?
The ISI is a 7-item questionnaire assessing the nature and impact of insomnia — difficulty falling asleep, staying asleep, satisfaction with sleep, and daytime impairment. It is widely used in both research and clinics.
What ISI score indicates clinical insomnia?
Scores range 0-28. Common bands are: 0-7 no clinically significant insomnia, 8-14 subthreshold, 15-21 moderate, 22-28 severe. A score of 15 or more usually warrants professional attention.
Is the ISI a diagnosis?
No. The ISI quantifies how much your sleep is bothering you. Insomnia disorder is diagnosed clinically, taking history, duration, and other conditions into account.
Should I track my ISI over time?
Yes — the ISI is designed to be sensitive to change, for example during CBT-I (cognitive behavioral therapy for insomnia). Retaking it every one or two weeks gives a useful trend line.
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