Insomnia Test (ISI)

What Is the Insomnia Severity Index (ISI)?

The ISI measures a patient's perception of insomnia severity. Bastien, Vallières & Morin developed it in 2001. It is one of the more commonly used insomnia assessments out there.

Scale Structure

The ISI contains 7 items covering the core dimensions of insomnia:

• Sleep difficulty severity (Q1-Q3): difficulty falling asleep, staying asleep, early morning awakening
• Sleep satisfaction (Q4): subjective satisfaction with current sleep pattern
• Daytime functioning impact (Q5): interference with daily functioning
• Noticeability (Q6): how noticeable the impairment is to others
• Distress (Q7): level of worry/distress about the sleep problem

Scoring

Each item rated 0-4, total score 0-28. Higher scores indicate more severe insomnia.

Clinical Cutoffs

• 0-7: No clinically significant insomnia
• 8-14: Mild to moderate insomnia symptoms
• 15-21: Moderate insomnia (warrants evaluation and treatment)
• 22-28: Severe insomnia (immediate professional help recommended)

Psychometric Properties

Validation data (Bastien et al., 2001):

• Internal consistency: α = 0.90-0.91
• Test-retest reliability: r = 0.83
• Good convergent validity with sleep diary measures
• Good sensitivity and specificity at various cutoffs

Reference

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.

Morin, C. M. (1993). *Insomnia: Psychological Assessment and Management*. New York: Guilford Press.