The Insomnia Severity Index (ISI) is a 7-item questionnaire developed by Morin and colleagues (2011) to assess the severity of insomnia and its daytime impact. It asks about the past two weeks, covering sleep onset, maintenance, early waking, satisfaction, noticeability, worry, and interference with daily life. Scores range from 0 to 28. Source: Morin et al., 2011 (PubMed).
How to use it: Answer for the last two weeks as honestly as you can. It is a self-check, not a performance test.
Reading your score: The bands range from no clinical insomnia to severe insomnia. They describe symptom severity, not a diagnosis.
Limitations: The ISI is a self-report screening tool. It cannot rule sleep disorders in or out and is not a substitute for a sleep-medicine evaluation.
When to seek help: If your score is in the moderate or severe range, or sleep problems affect your days, consider a clinician or sleep specialist. If sleep loss is linked to low mood or hopelessness, contact 988 (US) right away.
Related: Our WHO-5 Well-Being Index and Mental Health Help (US).