Insomnia Severity Index (ISI)
Psychology: Health & SleepReliability: alpha 0.903 sample items
About this scale
A 7-item self-report measure of insomnia severity, sleep dissatisfaction, daytime impairment, and worry about sleep over the past two weeks.
Sample item(s)
“Difficulty falling asleep”
“Difficulty staying asleep”
“Sleep dissatisfaction”
Reliability
Reported internal consistency: alpha 0.90. As a rule of thumb, Cronbach’s α ≥ .70 is considered acceptable, ≥ .80 good, and ≥ .90 excellent for established measures.
Notes
Free for academic use.
Source & 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, Vol. 2, No. 4, pp. 297–307.
Bastien, Vallières & Morin (2001): ISI. Sleep Medicine, 2(4), 297–307.
Source. Scale details are summarised from the publication cited above. Always consult the original source for the full item set, scoring, and permission to use.
Use it in your research
Need to check the reliability or psychometrics of this scale in your own data? Use the free DrAIStudio research tools:
Cronbach’s alpha calculator
All statistical calculators
Search the full Scale Atlas
Academic writing humanizer