Insomnia Severity Index
ISIA 7-item self-report measure of the nature, severity, and impact of insomnia over the past two weeks, widely used as an outcome measure in insomnia research.
Ready-to-cite methods sentence
Reliability & validation
Known limitations
A self-report screening/outcome measure rather than a diagnostic or objective (polysomnographic) assessment; cutoffs differ slightly between community and clinical samples.
Original citation
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.
https://doi.org/10.1016/S1389-9457(00)00065-4Questions researchers ask
What does the ISI measure?
A 7-item self-report measure of the nature, severity, and impact of insomnia over the past two weeks, widely used as an outcome measure in insomnia research.
How many items does the ISI have?
The Insomnia Severity Index (ISI) has 7 items.
Is the ISI free to use?
The ISI is free to use for non-commercial academic research. You don't need to pay a license fee, but you should always cite the original publication.
Is the ISI reliable?
Validation studies report Cronbach's α of 0.9. See the reliability section for the population studied and full statistics.
Who developed the ISI, and how do I cite it?
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. https://doi.org/10.1016/S1389-9457(00)00065-4
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Library entry verified July 2026. Metadata is provided for reference; item wording is available inside Folio Surveyor, subject to each instrument's licensing.