The 7-question Insomnia Severity Index — the same clinical tool used by sleep specialists worldwide. Rate your sleep over the past 2 weeks.
Insomnia is the most common sleep disorder worldwide, affecting approximately 10–15% of adults chronically and 30–35% episodically. Despite its prevalence, insomnia is significantly undertreated — most people either accept it as a permanent feature of their life, self-medicate with alcohol or OTC sleep aids, or pursue treatments that don't address the underlying cause. This guide covers what insomnia actually is, how to accurately assess its severity, and what treatments have the strongest evidence.
Insomnia is not simply "having trouble sleeping occasionally." The clinical definition, per DSM-5 and ICSD-3, requires: difficulty initiating sleep, maintaining sleep, or waking too early (early morning insomnia) — occurring at least 3 nights per week, for at least 3 months, despite adequate opportunity for sleep, and causing meaningful daytime impairment. This specificity matters because it distinguishes treatable chronic insomnia from normal situational sleep disruption (which all people experience).
Insomnia types are categorized by which phase of sleep is affected. Sleep onset insomnia (difficulty falling asleep) is most common and strongly associated with anxiety and hyperarousal. Sleep maintenance insomnia (waking during the night) is common in older adults, those with sleep apnea, and those with elevated cortisol from stress. Early morning waking (waking 1–2 hours before intended time and being unable to return to sleep) is classically associated with depression.
The ISI used in this calculator was developed by Charles Morin et al. and first validated in 2001. It has since been translated into over 30 languages and validated across diverse clinical populations. The ISI's 7 items assess the three main insomnia symptoms plus their functional consequences — providing a comprehensive severity picture in under 2 minutes.
The validated scoring cutoffs are: 0–7: no clinically significant insomnia; 8–14: subthreshold insomnia (clinically meaningful but below diagnostic threshold — warrants attention and self-help); 15–21: moderate clinical insomnia (clinical assessment and CBT-I strongly recommended); 22–28: severe clinical insomnia (clinical intervention urgently needed). This calculator implements these exact cutoffs with original sensitivity/specificity data.
Cognitive Behavioral Therapy for Insomnia (CBT-I) is recommended as first-line treatment by the American Academy of Sleep Medicine, the American College of Physicians, and the British Sleep Society. It resolves chronic insomnia in 70–80% of cases — with better long-term outcomes than any sleep medication and zero dependency risk. It works by addressing the perpetuating factors that maintain insomnia rather than just suppressing symptoms temporarily.
CBT-I has five components: Sleep restriction therapy — initially limiting time in bed to match actual sleep time, then gradually extending; Stimulus control — breaking the bed-wakefulness association; Cognitive restructuring — addressing catastrophic thoughts about sleep; Sleep hygiene education; and Relaxation training (including PMR and breathing techniques). A full course takes 6–8 weekly sessions with a trained therapist, but validated digital CBT-I programs have also shown clinical efficacy.
Sleep medications (benzodiazepines, non-benzodiazepine "Z-drugs" like zolpidem, antihistamines) produce short-term symptom relief but don't address the underlying causes of insomnia. Long-term use produces tolerance, dependency, and rebound insomnia when discontinued. The ACP explicitly recommends trying CBT-I before sleep medications. Melatonin has a modest effect on sleep onset timing (not sedation) and is appropriate for circadian-phase issues but shows minimal efficacy for classic insomnia. OTC antihistamines (diphenhydramine) rapidly produce tolerance within 3–4 days.