Usage conditions apply. The ISI is copyrighted by Professor Charles M. Morin (1993, 1996) and is distributed by Mapi Research Trust through its ePROVIDE platform. It is free to use in individual clinical practice, provided it is reproduced in full with the original copyright notice. Commercial users and funded academic research require a licence agreement and user fee, arranged via eprovide.mapi-trust.org. This is why the ISI differs from fully public-domain tools such as the PHQ-9: check your use case before embedding it in products, apps or funded studies.
Over the last two weeks, how often have you been bothered by…
01
Severity of your difficulty falling asleep.
Item score-
02
Severity of your difficulty staying asleep.
Item score-
03
Severity of your problem waking up too early.
Item score-
04
How satisfied or dissatisfied are you with your current sleep pattern?
Item score-
05
How noticeable to others do you think your sleep problem is in terms of impairing the quality of your life?
Item score-
06
How worried or distressed are you about your current sleep problem?
Item score-
07
To what extent do you consider your sleep problem to interfere with your daily functioning currently?
Item score-
Scored locally in your browser - nothing is sent until you choose to.
0 of 7 answered
0 / 28
ISI0 / 7
Over the last two weeks, how often have you been bothered by…
01
Severity of your difficulty falling asleep.
Item score-
02
Severity of your difficulty staying asleep.
Item score-
03
Severity of your problem waking up too early.
Item score-
04
How satisfied or dissatisfied are you with your current sleep pattern?
Item score-
05
How noticeable to others do you think your sleep problem is in terms of impairing the quality of your life?
Item score-
06
How worried or distressed are you about your current sleep problem?
Item score-
07
To what extent do you consider your sleep problem to interfere with your daily functioning currently?
The Insomnia Severity Index (ISI) is a seven-item self-report measure of the perceived severity of insomnia over the previous two weeks. It covers difficulty falling asleep, difficulty staying asleep, early-morning awakening, satisfaction with the current sleep pattern, how noticeable the problem is to others, distress about the problem, and interference with daily functioning. Each item is rated 0-4, giving a total of 0-28.
The ISI deliberately captures the patient's subjective appraisal of sleep rather than objective sleep parameters. This matches how insomnia disorder is defined clinically: the diagnosis rests on dissatisfaction with sleep together with daytime distress or impairment, not on polysomnography. Because roughly half the items address daytime consequences and appraisal, the ISI is sensitive to the aspects of insomnia patients seek help for.
02 - Origin & purpose
Where it comes from.
The ISI was developed by Professor Charles M. Morin and first appeared in his 1993 volume Insomnia: Psychological Assessment and Management. The formal validation was published by Bastien, Vallières and Morin in 2001 in Sleep Medicine, which evaluated internal consistency, concurrent validity against sleep diaries, and sensitivity to change across treatment studies.
It was designed as a brief outcome measure for insomnia research, and that is where it has become dominant: the ISI is the de facto standard endpoint in trials of cognitive behavioural therapy for insomnia (CBT-I) and in pharmacological insomnia studies. In routine care it serves the same purpose - quantifying baseline severity and tracking response to treatment.
03 - Scoring & cutoffs
How scoring works.
The seven items are summed to a 0-28 total; there are no reverse-scored items and no subscales in routine use. The conventional severity bands are shown in the table below. For case-finding, Morin and colleagues (2011) found a cutoff of 10 optimal in a community sample (86.1% sensitivity, 87.7% specificity). In primary care, Gagnon and colleagues (2013) found a higher cutoff of 14 optimal for detecting clinical insomnia (82.4% sensitivity, 82.1% specificity) - worth bearing in mind when interpreting scores from screening versus treatment-seeking populations.
Score
Severity
Interpretation
0–7
No insomnia
No clinically significant insomnia.
8–14
Subthreshold
Subthreshold insomnia.
15–21
Moderate
Clinical insomnia of moderate severity.
22–28
Severe
Severe clinical insomnia.
04 - Validation evidence
How well it performs.
The ISI's psychometrics have been examined in community, clinical and primary-care samples. The original validation reported acceptable internal consistency and good convergence with sleep-diary measures; subsequent larger studies have reported excellent internal consistency and established the ISI's ability to detect cases and measure treatment response.
α = 0.90-0.92
Internal consistency
Cronbach's alpha was 0.90 in a community sample and 0.91 in a clinical sample (Morin et al., 2011), and 0.92 in primary care (Gagnon et al., 2013).
86.1% / 87.7%
Sensitivity / specificity
At the community screening cutoff of ≥10 for detecting insomnia cases (Morin et al., 2011).
r = 0.32-0.91
Convergent validity
Item-level correlations between ISI items and corresponding sleep-diary indicators in the original validation (Bastien et al., 2001), which reported α = 0.74 in treatment-seeking samples.
−8.4 points
Treatment response
A reduction of 8.4 points (95% CI −7.1 to −9.4) corresponded to moderate improvement as rated by an independent assessor (Morin et al., 2011).
05 - How it compares
How it compares to the alternatives.
Instrument
Items
Time
When to reach for it
ISI
7
~2-3 min
Insomnia severity and treatment outcome. The default for quantifying insomnia and tracking CBT-I response.
PSQI
19
~5-10 min
Global sleep quality over the past month across seven components. Reach for it when you need a broad picture of sleep quality rather than insomnia severity specifically.
SCI
8
~2 min
Screens for DSM-5 insomnia disorder; freely available (Espie et al., 2014). Reach for it as a free screening alternative aligned to DSM-5 criteria.
AIS
8
~3 min
ICD-10-based insomnia symptom scale. An alternative brief symptom measure.
Sleep disturbance frequently travels with depression - reach for the PHQ-9 when low mood is part of the picture.
06 - When to use it
Right tool, wrong tool.
The ISI is a severity and outcome measure for insomnia in adults. Use it to establish a baseline, quantify daytime impact and track response over time, alongside a clinical assessment rather than in place of one.
Reach for it when
-Quantifying the severity of suspected insomnia disorder
-Establishing a baseline before CBT-I or pharmacotherapy and monitoring response
-Capturing daytime impact and distress alongside night-time symptoms
-Research outcomes in insomnia trials
Reach for something else when
-Suspected obstructive sleep apnoea, narcolepsy or other hypersomnolence (consider the ESS and objective testing)
-Diagnosing insomnia disorder on its own - diagnosis requires clinical assessment
-Measuring objective sleep parameters (use diaries, actigraphy or polysomnography)
-Young children - the ISI was validated in adults
07 - Confidence & precision
Reading the score with care.
A single ISI score is an estimate, not a fixed quantity, and small fluctuations of a few points between administrations should not be over-interpreted. The best-evidenced marker of meaningful change comes from Morin and colleagues (2011): a reduction of about 8-9 points corresponded to moderate improvement judged by an independent assessor. In practice, treat single-digit shifts within a severity band cautiously, and look for movement of this magnitude - or a shift into a lower band sustained across visits - before concluding that treatment is working.
08 - Limitations
What it cannot tell you.
Entirely subjective: it does not measure sleep duration, latency or efficiency, and correlates only moderately with objective measures.
Optimal cutoffs vary by setting (10 in community screening versus 14 in primary care), so a single threshold cannot be applied everywhere.
Internal consistency in the original treatment-seeking samples was more modest (α = 0.74) than in later, larger samples.
It is a severity and outcome measure, not a diagnostic instrument, and does not differentiate insomnia from sleep disturbance secondary to other disorders.
It is copyrighted, which constrains use in commercial products and funded research without a licence.
09 - Licensing, explained
How licensing works.
The ISI is copyrighted by Professor Charles M. Morin (1993, 1996) and is distributed by Mapi Research Trust through its ePROVIDE platform. It is free to use in individual clinical practice, provided it is reproduced in full with the original copyright notice. Commercial users and funded academic research require a licence agreement and user fee, arranged via eprovide.mapi-trust.org. This is why the ISI differs from fully public-domain tools such as the PHQ-9: check your use case before embedding it in products, apps or funded studies.
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