Insomnia Severity Index Calculator

The Insomnia Severity Index (ISI) Calculator scores the seven-item self-report measure of insomnia severity developed by Charles Morin at Universite Laval. The ISI is the most widely used outcome measure in insomnia treatment research and clinical practice, providing a reliable and valid assessment of the nature, severity, and daytime impact of insomnia symptoms over the past two weeks. Insomnia is the most prevalent sleep disorder, affecting approximately 30 percent of adults at any given time with acute symptoms and 10 percent meeting criteria for chronic insomnia disorder (symptoms persisting three or more months with daytime impairment). The economic burden of insomnia in the United States exceeds $63 billion annually in lost workplace productivity alone, with additional healthcare costs of $2,000 to $3,000 per patient per year compared to those without insomnia. Despite its prevalence, insomnia remains underdiagnosed and undertreated. The ISI evaluates seven dimensions of insomnia on a 0-to-4 severity scale: difficulty falling asleep (sleep onset latency), difficulty staying asleep (sleep maintenance), early morning awakening, satisfaction with current sleep pattern, interference with daily functioning, noticeability of sleep impairment to others, and worry or distress about the sleep problem. The total score ranges from 0 to 28 and maps to four severity categories that guide clinical decision-making. The ISI has been validated against polysomnography (PSG), the gold-standard objective sleep measurement, showing moderate correlations (r = 0.32 to 0.55 depending on the PSG parameter). It is more strongly correlated with subjective sleep diary measures (r = 0.65 to 0.80), reflecting the fact that insomnia is fundamentally a subjective complaint even when objective sleep parameters are within normal limits. The ISI is the primary outcome measure in virtually all cognitive-behavioral therapy for insomnia (CBT-I) trials and is used by sleep clinics, primary care providers, behavioral health specialists, and researchers worldwide.

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1. 1Complete all seven items based on your sleep experience over the past two weeks. The first three items assess the three types of insomnia complaints: difficulty falling asleep at bedtime (sleep onset insomnia), difficulty staying asleep during the night (sleep maintenance insomnia), and waking up too early in the morning and being unable to return to sleep (early morning awakening insomnia). Each is rated from 0 (none) to 4 (very severe). These items capture the core symptom presentation and help differentiate between insomnia subtypes that may respond differently to specific interventions.
2. 2Rate your satisfaction with your current sleep pattern on item 4, from 0 (very satisfied) to 4 (very dissatisfied). This item captures the subjective quality component of insomnia, which may differ from the objective frequency of sleep disturbances. Some individuals with objectively mild sleep disruption experience severe dissatisfaction, while others with significant measurable disruption report adequate satisfaction. The discrepancy between objective and subjective assessment is a key feature of insomnia and an important treatment target.
3. 3Assess the impact of your sleep problems on daily functioning on item 5, rating how much your sleep difficulties interfere with daytime functioning (fatigue, concentration, mood, productivity) from 0 (not at all interfering) to 4 (very much interfering). This item is critical for clinical diagnosis because the DSM-5 diagnostic criteria for Insomnia Disorder require clinically significant distress or impairment in social, occupational, or other important areas of functioning. A score of 3 or 4 on this item alone may justify clinical intervention.
4. 4Evaluate the noticeability of your sleep impairment on item 6, rating how noticeable to others your sleep problem appears in terms of impairing your quality of life, from 0 (not at all noticeable) to 4 (very much noticeable). This external validation item helps calibrate self-perception against observable impact. Individuals who score high on this item are typically experiencing significant functional impairment that extends beyond their own awareness.
5. 5Rate your level of worry or distress about your sleep on item 7, from 0 (not at all worried) to 4 (very much worried). This item captures the cognitive-emotional component of insomnia, which is often the primary maintenance factor in chronic insomnia. Excessive worry about sleep creates a paradoxical arousal state that perpetuates the very insomnia it attempts to address. This cognitive hyperarousal is the primary target of CBT-I, the first-line treatment for chronic insomnia.
6. 6Sum all seven item scores to obtain the ISI total score (range 0-28). The calculator automatically classifies the total into one of four severity categories based on validated cutoffs: 0-7 (no clinically significant insomnia), 8-14 (subthreshold or mild insomnia), 15-21 (moderate clinical insomnia), and 22-28 (severe clinical insomnia). Scores of 15 or above indicate clinically significant insomnia that warrants treatment, with CBT-I as the recommended first-line intervention per American Academy of Sleep Medicine guidelines.
7. 7Review the treatment recommendations based on your severity classification. For subthreshold insomnia (8-14), sleep hygiene education and stimulus control may be sufficient. For moderate insomnia (15-21), structured CBT-I (typically 6-8 sessions) is strongly recommended and is more effective than medication for long-term outcomes. For severe insomnia (22-28), combined CBT-I and short-term pharmacotherapy may be appropriate, with a plan to taper medication as CBT-I skills are established. The calculator provides referral information for CBT-I providers (CBTI Directory, VA CBT-I Coach app) and contextualizes the score against population norms.

• !The most common misuse of the ISI is interpreting it as a diagnostic instrument rather than a severity measure. The ISI score alone cannot diagnose Insomnia Disorder, which requires meeting specific DSM-5 criteria including symptom duration of at least three months, occurrence on at least three nights per week, and the absence of another sleep disorder, medical condition, or substance that better explains the symptoms. A high ISI score in a patient with untreated sleep apnea, restless legs syndrome, or medication side effects requires treatment of the underlying condition before insomnia-specific interventions are applied.
• !Many clinicians and researchers fail to distinguish between the ISI two-week recall period and the sleep diary, which provides night-by-night data. The ISI is designed as a summary measure of average severity over two weeks and should not be administered more frequently than every two weeks. Using it weekly or more often reduces its reliability and may capture normal night-to-night variability rather than meaningful change. For more granular tracking, use a daily sleep diary alongside periodic ISI assessments.
• !A frequently overlooked issue is that the ISI does not assess sleep duration directly. An individual who sleeps 5 hours per night but falls asleep quickly, stays asleep, wakes at the desired time, and is satisfied with their sleep would score 0 on the ISI despite objectively short sleep. This pattern, sometimes called short sleep duration with minimal complaint, may still carry health risks (cardiovascular, metabolic, cognitive) even in the absence of subjective insomnia. The ISI should be supplemented with objective sleep duration data when comprehensive sleep health assessment is the goal.