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Compliance and documentation

How to use the Insomnia Severity Index (ISI) assessment

Learn more about the ISI assessment and how you can incorporate it into your practice.

October 4, 2024 • Updated on August 29, 2025

7 min read

Sleep and mental health go hand in hand. Conditions like insomnia can contribute to mental health symptoms, while mental health diagnoses can cause difficulty sleeping. In either case, if you’re concerned about a client’s sleep, you may consider conducting a formal assessment. 

The ISI, or Insomnia Severity Index, is one tool you can use to gain a better understanding of someone’s sleep so you can better support them as a therapist. Below, learn more about the ISI assessment and how you can incorporate it into your practice.

What is ISI?

The ISI is a seven-question questionnaire that assesses symptoms of insomnia on a five-point scale. It’s used to screen clients for insomnia, to determine the severity of someone’s insomnia, and to monitor changes in these symptoms (and in so doing, adjust the client’s treatment plan as needed). 

It’s a self-administered assessment, which means the client fills it out on their own, marking the symptoms they’re experienced in the last two weeks and how frequently they’ve experienced them. Then, a provider scores the assessment based on the client’s answers. 

Studies have found the ISI to be a reliable predictor of insomnia, with results consistently aligning with experts’ diagnoses.

ISI assessment

The ISI assessment includes the following questions and prompts clients to answer based on their sleep over the last month. Answer choices vary based on the question. 

The first three questions rate a person’s severity of specific sleep difficulties:

1. Difficulty falling asleep

2. Difficulty staying asleep

3. Problem waking up too early in the morning 

Choices include “none,” “mild,” “moderate,” “severe,” and “very severe.” 

4. How satisfied or dissatisfied are you with your current sleep pattern? 

Choices include “very satisfied,” “satisfied,” “neutral,” “dissatisfied,” and “very dissatisfied.” 

5. To what extent do you consider your sleep problem to interfere with your daily functioning (e.g. daytime fatigue, ability to function at work/daily chores, concentration, memory, mood). 

Choices include “not at all interfering,” “a little interfering,” “somewhat interfering,” “much interfering,” and “very much interfering.”

6. How noticeable to others do you think your sleep problem is in terms of impairing your quality of life? 

Choices include “not at all noticeable,” “a little noticeable,” “somewhat noticeable,” “much noticeable,” and “very much noticeable.”

7. How worried/distressed are you about your current sleep problem? 

Choices include “not at all,” “a little,” “somewhat,” “much,” and “very much.”

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ISI scoring

Each answer on the assessment is measured on a five-point Likert scale and assigned a certain number of points.

​​When each answer is assigned a point value, the total score for the ISI assessment can range from 0–28. In general, the higher the score, the more severe a person’s insomnia.

0-7: No clinically significant insomnia 

8-14: Subthreshold insomnia

15-21: Clinical insomnia (moderate severity)

22-28: Clinical insomnia (severe)

Monitoring changes in ISI

While it’s often used as a tool for screening and diagnosing new clients, the ISI is also useful in re-assessing clients so you can adjust their treatment plan as needed. For example, if you began treating a client with insomnia six months ago, you can re-issue the ISI to determine the current severity of symptoms and adjust your treatment plan as needed. 

In order to work with patients with insomnia and administer this assessment effectively, providers should feel equipped to use evidence-based treatments available like CBT-I, or Cognitive Behavioral Therapy for Insomnia. For additional training on working with insomnia, there are online courses available on sites like PESI.

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Managing a practice can yield its fair share of sleepless nights. But Headway supports therapists with the overwhelming administrative burdens of insurance credentialing, billing, claims, and clawbacks — so you can rest easy and focus on providing great, connected care.

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This content is for general informational and educational purposes only and does not constitute clinical, legal, financial, or professional advice. All decisions should be made at the discretion of the individual or organization, in consultation with qualified clinical, legal, or other appropriate professionals.

© 2026 Therapymatch, Inc. dba Headway. All rights reserved. No part of this publication may be reproduced without permission.

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