Insomnia Severity Index (ISI)
In plain English
Insomnia Severity Index (ISI) is a multi-item scale (7 items). What it claims to measure: Perceived severity of insomnia over a recent recall period (typically two weeks), covering severity of sleep-onset, sleep-maintenance and early-morning-waking difficulty, satisfaction with sleep, interference with daytime functioning, noticeability of the ... Licence for an employer or vendor: fee-bearing (verified 2026-07-12).
The published evidence is strongest for criterion validity against a reference standard and internal consistency; moderate for structural validity, convergent and discriminant validity, test-retest reliability, measurement invariance and responsiveness to change. No published evidence was located for criterion validity against organisational outcomes (absence, turnover, performance): the registry searched and found none in the sweep to date, so if you need that property evidenced, this instrument does not yet carry it. The evidence base for structural validity and measurement invariance is contested in the published literature. 2 of the 7 graded properties rest on evidence from clinical, student or otherwise non-working samples; where the property is sensitive to population that evidence cannot carry a High grade, and the reason is stated on each cell below. 2 of the 7 graded properties rest on adult general-population samples rather than samples of working adults; the flag says so on each cell.
Grades summarise the published evidence for this instrument on its own terms; they are not comparable across instruments, and this page makes no recommendation. Whether an instrument fits your workforce is a judgement this registry informs but cannot make. Full evidence, with citations, below. This summary is generated from the record's data, not written by hand.
Identity
Version: 7-item ISI (standard fielded form; original French-language validation Bastien 2001; a 6-item two-factor scoring and several brief derivatives such as ISI-3 exist but the 7-item form is canonical)
Structure: 7
Original citation: Bastien CH, Vallieres A, Morin CM (2001), Sleep Medicine 2(4):297-307, doi:10.1016/s1389-9457(00)00065-4
Steward / publisher: Charles M. Morin (copyright holder); distributed under licence by Mapi Research Trust via the ePROVIDE platform
Licence status (verified 2026-07-12): Proprietary, not open access. The ISI is copyrighted by Charles M. Morin (dates given on distributor documents as 1993 and 1996) and is distributed by Mapi Research Trust on behalf of the developer and copyright owner. On the current Mapi/ePROVIDE steward pages a licence agreement must be completed and a user fee is required for commercial and funded academic users, with a screenshot review agreement additionally required of commercial users; distributor documentation states that unauthorised modification, reproduction and use is prohibited and material is used with permission. Terms therefore differ by user type and require a request to Mapi before use. No open Creative Commons or public-domain release was found on the steward platform.
Constructs claimed
Perceived severity of insomnia over a recent recall period (typically two weeks), covering severity of sleep-onset, sleep-maintenance and early-morning-waking difficulty, satisfaction with sleep, interference with daytime functioning, noticeability of the impairment to others, and worry or distress about the sleep problem. Used both as a screening measure and as an outcome/change measure.
Evidence
Structural validity Moderatecontestedevidence form: mixed
direct shift workers and nurses; also dementia caregivers, Black Women's Health Study cohort, menopausal women, pregnant women, college students and trial samples (flag basis: very large occupational sample of Korean shift workers; Saudi nurses; Spanish dementia-caregiver sample; menopausal women; pregnant women; US college students)
The ISI factor structure is genuinely contested: the systematic review and meta-analysis by Manzar and colleagues catalogued roughly 13 disparate reported models and concluded that, on pooled confirmatory evidence, a two-factor solution is the more robust representation of dimensionality than a three-factor one, while noting widespread methodological omissions across primary studies (Manzar 2021). Individual studies variously report one factor (for example a Spanish dementia-caregiver sample, Jimenez 2021; a large Black Women's Health Study cohort where a one-factor model fitted but not robustly, Yusufov 2021), two factors of severity and daytime impact (menopausal women, Otte 2019; pregnant women, Shinohara 2023; Saudi nurses, Albougami 2019; the six-item reworking in the lemborexant trials, Lenderking 2024), and three factors (a Taiwan/Hong Kong/Canada cross-cultural analysis, Chen 2015; US college students, Emert 2024). In a very large occupational sample of Korean shift workers exploratory analysis returned a single ISI factor (Park 2019). The dominant modern reading is a two-factor severity/impact structure, but the number of factors is demonstrably sample-dependent, which is itself the graded finding.
Convergent and discriminant validity Moderatewell-establishedevidence form: canonical
general population-based validation sample; also clinical and college student samples (flag basis: population-based and clinical validation; US college students)
Convergent validity is well supported. Total ISI score correlates significantly with sleep-diary indices, fatigue, quality of life, anxiety and depression in the population-based and clinical validation (Morin 2011). In US college students the ISI total showed weak-to-strong correlations with other sleep-disturbance indicators (r approximately 0.25 to 0.62) and weak-to-moderate correlations with psychosocial measures (r approximately 0.10 to 0.57), with analogous ISI and sleep-diary items correlating around r=0.40 to 0.45; the authors caution about overlap with general psychological distress (Emert 2024). Indian and other adaptations report strong correlation with the Pittsburgh Sleep Quality Index (for example r approximately 0.45) (Veqar 2017). Discriminant validity is comparatively less tested, and the overlap between ISI scores and depression/anxiety measures is a recurring caution rather than clean separation.
Criterion validity: reference standard Highwell-establishedevidence form: canonical
general community sample; also clinical, primary care and college student samples (flag basis: community sample; clinical sample; primary care patients; US college students)
Criterion validity against a diagnostic reference standard is the ISI's strongest evidence. A community-sample cut-off of 10 gave 86.1% sensitivity and 87.7% specificity (the abstract does not state the reference standard for the community sample), and in the clinical sample, where diagnosis rested on interview, sleep diaries and polysomnography, the ISI discriminated insomnia from good sleepers (Morin 2011). In primary care patients, against a semi-structured diagnostic interview, an optimal cut-off of 14 gave 82.4% sensitivity and 82.1% specificity, area under the curve 0.87, with moderate agreement (kappa=0.62) (Gagnon 2013). A meta-analysis of 19 studies (4693 participants) pooled ISI sensitivity at 88% (95% CI 0.79 to 0.93) and specificity at 85% (0.68 to 0.94) against reference standards, comparable to the Athens Insomnia Scale and Pittsburgh Sleep Quality Index (Chiu 2016). Optimal cut-offs vary substantially by population (for example >=8 in US college students, Emert 2024), so a single universal threshold does not transport cleanly. The community sample comprised 959 individuals and the clinical sample 183 insomnia patients and 62 good-sleeper controls (Morin 2011); the primary care validation screened 410 patients, of whom 101 completed the diagnostic interview (Gagnon 2013); the meta-analysis pooled a diagnostic odds ratio of 41.93 (95% CI 8.77 to 200.33) for the ISI (Chiu 2016); and the college-student study reported an area under the curve of 0.999 at the 8 or above cut-off but gives no sample size in its abstract (Emert 2024).
High precondition (rubric 1.6): the cited studies that meet the High precondition, each with a sample size and a statistic of this property; on this population-sensitive property at least one is working-adults or general.
| Study | Sample | Statistic | Population | DOI |
|---|---|---|---|---|
| Chiu 2016 | 19 studies, 4693 participants (across ISI, AIS and PSQI) | ISI pooled sensitivity 88% (95% CI 0.79-0.93), specificity 85% (0.68-0.94), DOR 41.93 (8.77-200.33) | other | 10.1016/j.jpsychores.2016.06.010 |
| Morin 2011 | community sample 959; clinical sample 183 insomnia patients and 62 controls | cut-off 10: sensitivity 86.1%, specificity 87.7% in community sample; change score -8.4 (95% CI -7.1 to -9.4) for moderate improvement in clinical sample; alpha 0.90 and 0.91 | general | 10.1093/sleep/34.5.601 |
| Gagnon 2013 | 410 patients; subsample 101 with semistructured interview | AUC 0.87; cut-off 14: 82.4% sensitivity, 82.1% specificity, 82.2% agreement; kappa 0.62; alpha 0.92 | other | 10.3122/jabfm.2013.06.130064 |
Criterion validity: organisational Absent (searched; none found in the sweep to date)untestedevidence form: canonical
absence type: population-general searched; none found in the sweep to date
No evidence was located in the latest review pass validating the ISI against organisational or work outcomes such as sickness absence, staff turnover, or objective job performance. Occupational studies retrieved used the ISI within workforce samples (for example over 12,000 Korean shift workers screened at occupational health examinations, Park 2019; Saudi nurses, Albougami 2019) but assessed its internal structure and reliability, not its association with work outcomes. The absence of criterion validation against organisational endpoints is the finding, and it matters directly for a workplace-wellbeing registry: the ISI is validated as an insomnia screener, not as a predictor of work-relevant outcomes.
Internal consistency Highwell-establishedevidence form: canonical
direct nurses; also population-based, clinical, primary care, dementia caregiver, Black women and older adult samples (flag basis: Saudi nurses; population-based and clinical samples; primary care patients; Spanish dementia caregivers; older Indonesian adults)
Internal consistency is consistently high. Cronbach alpha was 0.90 and 0.91 in the population-based and clinical samples (Morin 2011), 0.92 in primary care patients (Gagnon 2013), and the meta-analysis reported a high pooled alpha across studies (Manzar 2021). Values in adaptation and subgroup studies span roughly 0.75 to 0.96, for example 0.75 to 0.78 for the two ISI factors among Saudi nurses (Albougami 2019), 0.78 in Spanish dementia caregivers (Jimenez 2021), omega approximately 0.89 in Black women (Yusufov 2021), and 0.96 in older Indonesian adults (KemalaSari 2026). Alpha at the upper end (>0.95) may signal item redundancy in a short scale. Sample sizes were 959 community participants and 183 clinical patients plus 62 controls (Morin 2011), 410 primary care patients (Gagnon 2013), 134 Saudi nurses (Albougami 2019), 271 Spanish dementia caregivers (Jimenez 2021), 29,500 Black women, 28,214 without and 1286 with a cancer history, with omega 0.892 and 0.896 respectively (Yusufov 2021) and 510 Indonesian older adults, where the ICC was also 0.96 (KemalaSari 2026); the meta-analysis covered 20 studies without giving the pooled alpha value in its abstract (Manzar 2021).
High precondition (rubric 1.6): the cited studies that meet the High precondition, each with a sample size and a statistic of this property.
| Study | Sample | Statistic | DOI |
|---|---|---|---|
| Albougami 2019 | 134 | alpha 0.75 and 0.78 for the two ISI factors | 10.1007/s11325-019-01812-8 |
| Jimenez 2021 | 271 | alpha 0.78 | 10.1016/j.sleep.2021.03.036 |
| Morin 2011 | 959 community; 183 clinical plus 62 controls | alpha 0.90 and 0.91 | 10.1093/sleep/34.5.601 |
| Yusufov 2021 | 29,500 (28,214 without cancer history, 1286 cancer survivors) | omega 0.896 (with cancer history) and 0.892 (without) | 10.1111/jsr.13421 |
| Gagnon 2013 | 410 (101 interviewed) | alpha 0.92 | 10.3122/jabfm.2013.06.130064 |
| KemalaSari 2026 | 510 | alpha 0.96; ICC 0.96; item-total r 0.75 or more | 10.7717/peerj.20473 |
Test-retest reliability Moderatewell-establishedevidence form: mixed
indirect medical outpatients, college students, university students and older adults; no working-adult or general-population sample (flag basis: Danish medical outpatients; US college students; Indian university students; older Indonesian adults)
| Coefficient | Type | Interval | Sample | Population | Evidence form |
|---|---|---|---|---|---|
| 0.90 (95% CI 0.87 to 0.93) | ICC | 2 weeks | 163 (retest completers of 249) | Danish medical outpatients (ISI-DK) | derivative |
| 0.87 | ICC | reported as test-retest interval in study III (short interval) | US college sample (Experiment III) | US college students | canonical |
| 0.84 | ICC | 1 week | 25 poor sleepers | Indian university students | derivative |
| 0.96 | ICC | not clearly specified (short interval) | 510 | older Indonesian adults (Indonesian ISI) | derivative |
Test-retest reliability is repeatedly reported as good to excellent (ICC roughly 0.84 to 0.96) across two-week and one-week intervals, but every retained coefficient comes from a student, clinical, older-adult or community sample rather than a working-adult cohort, and some rest on small retest subsamples. It is a genuine and reproducible property, downgraded for population indirectness and reliance on translated/derivative versions.
Measurement invariance Moderatecontestedevidence form: canonical
direct nurses; also pregnant women and midlife women with hot flushes (flag basis: gender in Saudi nurses; pregnant Japanese women; midlife women with hot flushes)
Invariance evidence is moderate and mostly favourable within its (indirect) samples. Strong (scalar-level) cross-cultural invariance held across Taiwanese, Hong Kong and Canadian samples for a three-factor model (Chen 2015). A two-factor model showed configural, metric, scalar and partial strict invariance across gender in Saudi nurses (Albougami 2019). Measurement and structural invariance held across parity and across two perinatal time points one week apart in pregnant Japanese women (Shinohara 2023). A two-factor structure was largely invariant across Black and White midlife women with hot flushes, with one item (difficulty falling asleep) behaving differently (Otte 2019). Because the underlying factor model itself is contested and sample-dependent, invariance conclusions are conditional on the model chosen, and occupational invariance is untested.
Sub-grades (evidence differs by subgroup):
- {"subgroup": "across culture/language", "grade": "Moderate", "note": "scalar invariance reported across Taiwan, Hong Kong, Canada (Chen 2015)"}
- {"subgroup": "across sex", "grade": "Low", "note": "partial strict invariance in a single Saudi-nurse sample (Albougami 2019)"}
- {"subgroup": "across occupation", "grade": "Absent", "note": "no occupational-group invariance evidence located"}
Responsiveness and MIC Moderatewell-establishedevidence form: mixed
indirect treatment and clinical-trial samples; no working-adult or general-population sample (flag basis: phase III lemborexant trials; similar trial populations)
Responsiveness is a comparative strength: the ISI was designed and validated as a treatment-outcome measure, detecting change across behavioural and pharmacological treatment against sleep diaries and polysomnography (Bastien 2001). For interpretability, Morin and colleagues estimated that a change of about -8.4 points (95% CI -7.1 to -9.4) on the 7-item ISI corresponded to moderate clinician-rated improvement (Morin 2011). A later clinical-trial re-analysis (two phase III lemborexant trials, N=1956) favoured a 6-item two-factor scoring and derived a meaningful within-individual change of a 5-point reduction on the 6-item version, noting that generalisability may be limited to similar trial populations (Lenderking 2024). The systematic review noted that responsiveness and interpretability remain less completely reported than reliability and criterion validity across insomnia instruments generally (Ali 2020). The minimal important change is therefore established but version- and population-dependent (approximately 7 to 8.4 points on the 7-item form; approximately 5 points on the 6-item form).
Populations, languages and norms
The ISI is among the most extensively studied insomnia instruments and has been translated and psychometrically evaluated in a large number of languages and populations, including French and English (originating), Spanish, Swedish, Portuguese, Arabic, Korean, Chinese, Japanese, Danish, Indonesian and others, and across clinical, primary-care, community, student, cancer, caregiver, menopausal, perinatal and occupational samples (Ali 2020; Manzar 2021; Morin 2011; Chen 2015). Community reference values and case-finding cut-offs are available (for example cut-off 10 for community case detection, 14 in primary care), but these are population-specific and no working-adult normative reference set was located in the latest review pass in any country. Population coverage is broad; occupational norms are the gap. Abstract-level sample counts are a community sample of 959 and a clinical sample of 183 insomnia patients plus 62 controls, where the cut-off of 10 gave 86.1% sensitivity and 87.7% specificity (Morin 2011); three samples from Taiwan, Hong Kong and Canada with strong invariance across cultures (Chen 2015); 20 studies in the structural validity meta-analysis (Manzar 2021); and 107 articles covering 31 instruments in the systematic review, which named the ISI among the most extensively evaluated (Ali 2020).
Criticisms and controversies
The principal, well-documented controversy is dimensionality: reported factor solutions range across one, two and three factors and are demonstrably sample-dependent, and a systematic review found frequent methodological shortcomings (failure to use or report EFA/CFA appropriately, neglect of multivariate normality and fit-based model selection) in the primary literature (Manzar 2021). This instability means invariance and change-score interpretation are conditional on the model chosen. A second issue is cut-off drift: optimal case-finding thresholds vary widely by setting (for example 8 in students, 10 in the community, 14 in primary care), so a single universal cut-off is not defensible (Emert 2024; Morin 2011; Gagnon 2013). Third, ISI scores overlap substantially with depression and anxiety measures, so treating insomnia severity as cleanly separable from general distress requires caution (Emert 2024). Finally, the MIC differs between the 7-item and 6-item scorings, which complicates cross-study comparison of treatment effects (Morin 2011; Lenderking 2024).
References (20)
- Bastien CH; Vallières A; Morin CM (2001). Validation of the Insomnia Severity Index as an outcome measure for insomnia research https://doi.org/10.1016/s1389-9457(00)00065-4
- Morin CM; Belleville G; Bélanger L; Ivers H (2011). The Insomnia Severity Index: psychometric indicators to detect insomnia cases and evaluate treatment response https://doi.org/10.1093/sleep/34.5.601
- Gagnon C; Bélanger L; Ivers H; Morin CM (2013). Validation of the Insomnia Severity Index in primary care https://doi.org/10.3122/jabfm.2013.06.130064
- Chiu HY; Chang LY; Hsieh YJ; Tsai PS (2016). A meta-analysis of diagnostic accuracy of three screening tools for insomnia https://doi.org/10.1016/j.jpsychores.2016.06.010
- Ali RM; Zolezzi M; Awaisu A (2020). A systematic review of instruments for the assessment of insomnia in adults https://doi.org/10.2147/NSS.S250918
- Lenderking WR; Savva Y; Atkinson MJ; Campbell R (2024). Re-examining the factor structure of the Insomnia Severity Index (ISI) and defining the meaningful within-individual change (MWIC) for subjects with insomnia disorder in two phase III clinical trials of the efficacy of lemborexant https://doi.org/10.1186/s41687-024-00744-6
- Chen PY; Yang CM; Morin CM (2015). Validating the cross-cultural factor structure and invariance property of the Insomnia Severity Index: evidence based on ordinal EFA and CFA https://doi.org/10.1016/j.sleep.2014.11.016
- Emert SE; Dietch JR; Bramoweth AD; Kelly K (2024). Psychometric evaluation of the Insomnia Severity Index in U.S. college students https://doi.org/10.1016/j.beth.2024.02.003
- Manzar MD; Jahrami HA; Bahammam AS (2021). Structural validity of the Insomnia Severity Index: a systematic review and meta-analysis https://doi.org/10.1016/j.smrv.2021.101531
- Park YM; Lee HJ (2019). Factor analysis of the Insomnia Severity Index and Epworth Sleepiness Scale in shift workers https://doi.org/10.3346/jkms.2019.34.e317
- Otte JL; Bakoyannis G; Rand KL; et al. (2019). Confirmatory factor analysis of the Insomnia Severity Index (ISI) and invariance across race: a pooled analysis of MsFLASH data https://doi.org/10.1097/GME.0000000000001343
- Shinohara H; Hada A; Minatani M; et al. (2023). The Insomnia Severity Index: factor structure and measurement and structural invariance across perinatal time points https://doi.org/10.3390/healthcare11081194
- Thakral M; Von Korff M; McCurry SM; et al. (2021). ISI-3: evaluation of a brief screening tool for insomnia https://doi.org/10.1016/j.sleep.2020.08.027
- Albougami A; Manzar MD (2019). Insomnia Severity Index: a psychometric investigation among Saudi nurses https://doi.org/10.1007/s11325-019-01812-8
- Jiménez-Gonzalo L; Romero-Moreno R; Pedroso-Chaparro MS; et al. (2021). Psychometric properties of the Insomnia Severity Index in a sample of family dementia caregivers https://doi.org/10.1016/j.sleep.2021.03.036
- Yusufov M; Recklitis CJ; Zhou ES; et al. (2021). A population-based psychometric analysis of the Insomnia Severity Index in black women with and without a history of cancer https://doi.org/10.1111/jsr.13421
- Kemala Sari N; Stepvia S; Ilyas MF (2026). Validity and reliability of Insomnia Severity Index among older adults in Indonesia https://doi.org/10.7717/peerj.20473
- Dieperink KB; Elnegaard CM; Winther B; et al. (2020). Preliminary validation of the Insomnia Severity Index in Danish outpatients with a medical condition https://doi.org/10.1186/s41687-020-0182-6
- Veqar Z; Hussain ME (2017). Validity and reliability of insomnia severity index and its correlation with Pittsburgh Sleep Quality Index in poor sleepers among Indian university students https://doi.org/10.1515/ijamh-2016-0090
- Chahoud M; Chahine R; Salameh P; Sauleau EA (2017). Reliability, factor analysis and internal consistency calculation of the Insomnia Severity Index (ISI) in French and in English among Lebanese adolescents https://doi.org/10.1016/j.ensci.2017.03.003
Record notes
Overall confidence: the ISI is a well-established, heavily validated insomnia screener and outcome measure with high internal consistency, strong criterion validity against diagnostic reference standards, good-to-excellent test-retest reliability, and established (if version-dependent) responsiveness and minimal important change. It is downgraded here for two reasons that bite for this registry: (1) population indirectness, essentially all evidence comes from clinical, primary-care, student, cancer, caregiver, perinatal or community samples, with no working-adult validation, normative data, or occupational invariance located; and (2) a genuinely contested factor structure. Organisational criterion validity (against absence, turnover, performance) is Absent/untested, which is the honest and important finding for a workplace deployment. The clinical origin means workplace deployment is a distinct context flagged in deployment_context_caveat. Licence verified against the Mapi Research Trust ePROVIDE steward page on 2026-07-12: proprietary, permission required, not open access.