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Insomnia Severity Index (ISI)
Availability
Please email the author for information about obtaining the instrument: Dr. Charles M. Morin, cmorin@psy.ulaval.ca
Classification
Supplemental: Parkinson's Disease (PD)
Short Description of Instrument
The Insomnia Severity Index is a brief 7 question self-report instrument that measures the patient's perception of insomnia.
Comments/Special Instructions
There are three versions of the ISI:
 
1) Self-administered and the patient evaluates their sleep pattern during the last two weeks.
 
2) Self-administered and the patient evaluates their sleep pattern during the last month.
 
3) Clinician completes all ISI items based on a clinical interview with the patient.
Scoring and Psychometric Properties
Scoring: The questionnaire includes 7 items rated on a 0-4 scale that evaluate the severity of sleep initiation, sleep maintenance, early awakening, own sleep satisfaction, sleep interference with daily functioning, sleep malfunction noticeable by others, and being worried about sleep problem.
 
Psychometric Properties: Each item is categorized in five degrees (from none to very severe). Total score 0-7 indicates normal sleep, 8-14 indicates subthreshold insomnia, 15-21 indicates moderate clinical insomnia, and 22-28 indicates severe insomnia.
Rationale/Justification
Strengths: Developed in 1985, and widely used in clinical and research settings.
 
Weaknesses: Does not cover all aspects of a complex symptom such as insomnia. Not specific for PD.
References
Key Reference:
Bastien CH, Vallieres A, Morin CM. Validation of the Insomnia Severity Index as an outcome measure for insomnia research. Sleep Med. 2001 Jul;2(4):297-307.
 
Document last updated August 2022