Seven questions covering sleep onset, sleep maintenance, early waking, satisfaction and daytime impact. The ISI is the most common primary patient-reported endpoint in insomnia trials, including digital CBT-I studies.
Free sandbox · No credit card · 21 CFR Part 11 aligned
Sleep problems · Week 6
Rate the current severity (last 2 weeks):
Difficulty falling asleep
0 None · 4 Very severe
Difficulty staying asleep
Problems waking up too early
ISI at a glance
The instrument
Insomnia is defined by the person's experience: trouble falling or staying asleep, waking too early, and distress or impairment during the day. Sleep laboratory measures capture only part of that, so regulators and researchers rely on patient-reported outcomes. The ISI covers both the night-time symptoms and the daytime consequences in seven questions, and its validated cut-offs make results easy to interpret.
It is used in trials of hypnotic drugs, in behavioural therapy studies, and increasingly in digital therapeutics trials of app-based cognitive behavioural therapy for insomnia, where it is often the primary endpoint. In all of them it sits alongside a nightly sleep diary that captures sleep onset latency, wake after sleep onset and total sleep time.
Sum the seven items (0 to 4 each) for a total of 0 to 28. Capture stores each answer as its coded value, so the total is a simple sum in analysis. Require all seven items on the form to avoid partial questionnaires.
Week 6 total
12 / 28
Structure
| Item | Topic | Scale |
|---|---|---|
| 1 | Severity of difficulty falling asleep | 0 none to 4 very severe |
| 2 | Severity of difficulty staying asleep | 0 to 4 |
| 3 | Severity of waking too early | 0 to 4 |
| 4 | Satisfaction with current sleep pattern | 0 very satisfied to 4 very dissatisfied |
| 5 | Interference with daily functioning | 0 to 4 |
| 6 | How noticeable the impairment is to others | 0 to 4 |
| 7 | Worry or distress about the sleep problem | 0 to 4 |
Topics paraphrased. Obtain the licensed ISI and official translations through Mapi Research Trust.
With a sleep diary
Capture runs visit-based questionnaires and recurring diaries in the same study. Schedule the ISI at baseline and every few weeks, and a short morning sleep diary daily, each with its own completion window and reminders that respect quiet hours.
When due
18:00
Your evening diary is open
Next day
18:00
Reminder: your diary is still open
Final notice
21:30
Last chance before the window closes
Quiet hours
22:00 to 08:00 in the participant's time zone
Stops
As soon as the task is completed
Digital therapeutics
Digital therapeutics companies running insomnia trials need the ISI collected independently of their own app, in a system with an audit trail. Capture keeps the endpoint separate from the intervention: participants use your app for therapy and answer the ISI in Capture from a secure link.
From: Capture.Study · Sleep and Recovery Study
Your questionnaire is ready
Hi Anna, your evening diary is open until midnight. Tap the button to start. The link signs you in, no password needed.
Open my tasksQuestions? Reply to reach your study site.
My tasks
Evening diary
Due tonight
Week 4 questionnaire
Opens Monday
Both are ready to schedule in the free sandbox.
Trial design
The ISI rarely stands alone. Insomnia trials combine it with a daily sleep diary that captures sleep onset latency, wake after sleep onset, number of awakenings, total sleep time and sleep efficiency night by night. The diary shows how sleep changes; the ISI shows whether the participant experiences the problem as less severe and less disruptive. Regulators and reviewers expect both perspectives.
A baseline period of one to two weeks of diary completion before randomisation is common. It confirms the participant has the sleep pattern the protocol requires, gives a stable baseline, and lets sites identify participants who will not complete daily entries before they are randomised.
Insomnia trials often see substantial improvement in the control arm, from regression to the mean, sleep hygiene effects of being in a study, and the act of monitoring sleep itself. Sample size assumptions should reflect that. The sample size calculator helps check how the expected difference between arms drives enrolment.
Because the ISI covers two weeks, give it at intervals of at least two weeks and use visit windows so late completion does not overlap the previous period. Completion windows with reminders keep this manageable without site staff chasing participants by phone.
Before go-live
Licensed through Mapi Research Trust; record details on the form.
Morning sleep diary scheduled daily with its own completion window.
Diary run-in before randomisation, with minimum completion rules.
For example remission below 8 and response above a 7-point drop.
Prevents partial questionnaires.
Preview the participant view in the sandbox before ethics submission.
Seven items rated 0 to 4 are summed for a total of 0 to 28.
0 to 7 no clinically significant insomnia, 8 to 14 subthreshold, 15 to 21 moderate and 22 to 28 severe clinical insomnia.
Commonly, remission is a total below 8 and response is a reduction of more than 7 points from baseline. Define them in your analysis plan.
The last two weeks.
No. It is copyrighted and licensed through Mapi Research Trust.
Yes. It is often the primary endpoint in app-based CBT-I trials, collected separately from the intervention app.
Keep exploring
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Epworth Sleepiness Scale template
Daytime sleepiness.
Sleep diary template
Nightly sleep diary.
EDC for sleep disorder trials
Sleep studies end to end.
GAD-7 eCRF template
Anxiety often measured alongside insomnia.
EDC for digital health trials
Digital therapeutics studies.
Build the ISI with a sleep diary on one schedule. Free sandbox, no credit card.