Eight everyday situations, each rated for the chance of dozing off. The Epworth Sleepiness Scale is the standard measure of daytime sleepiness in sleep apnoea, narcolepsy and insomnia research, and it takes two minutes on a phone.
Free sandbox · No credit card · 21 CFR Part 11 aligned
Daytime sleepiness · Baseline
Chance of dozing in each situation
Situation 1
0 would never doze · 3 high chance of dozing
Situation 2
Situation 3
ESS at a glance
The instrument
The ESS asks how likely the participant would be to fall asleep in eight situations that vary in how soporific they are, from reading or watching television to being a passenger in a car or sitting and talking to someone. The design captures a general tendency to fall asleep across ordinary life rather than sleepiness at one moment, which makes it useful for comparing people and for tracking change under treatment.
Sleep apnoea trials use it heavily, because excessive daytime sleepiness is one of the main symptoms that treatments such as airway devices and wake-promoting drugs aim to relieve. It is also standard in narcolepsy and idiopathic hypersomnia research, and a safety measure in trials of sedating drugs.
Sum the eight items. Scores above 10 indicate excessive daytime sleepiness, and higher scores mean more sleepiness. In treatment trials the endpoint is usually change from baseline or the proportion of participants moving into the normal range. Missing items prevent a valid total, so require all eight on the form.
Participants are asked to imagine how they would feel in a situation they have not been in recently. Put that instruction in the form's help text exactly as the licensed version states it, so participants do not skip items.
Baseline total
14 / 24
Build it in Capture
Each situation is a linear scale from 0 to 3 with the anchors shown, stored as coded values. The form runs as an ePRO on the participant's phone or on a clinic tablet, and the licence details are recorded on the form.
Evening diary
Question 3 of 8
How would you rate your fatigue today?
0 = no fatigue, 10 = worst imaginable
In a sleep study
Sleep trials usually combine a sleepiness scale, a sleep quality or insomnia questionnaire and a nightly sleep diary. In Capture they share one schedule: visit-based questionnaires at clinic visits and a recurring diary every morning in between.
EDC for sleep disorder trials| Assessment | Scr | BL | W2 | W4 | W8 | W12 |
|---|---|---|---|---|---|---|
| Epworth (ESS) | ||||||
| PSQI | ||||||
| Sleep diary | D | D | D | D | D | |
| Device adherence |
D = daily morning diary
Add the ESS, a sleep diary and visit windows, then preview on your phone.
As an endpoint
The ESS is a trait-like measure: it asks about usual behaviour in recent times, not about one night. That makes it well suited to detecting sustained change under treatment over weeks, and less suited to measuring the effect of a single dose. Most trials assess it at baseline and then every four weeks or at the end of a treatment period.
Because it is self-reported, the ESS is often paired with an objective measure of sleepiness such as a maintenance of wakefulness test in the sleep laboratory. The two answer different questions (how sleepy people feel in daily life versus how well they stay awake under test conditions), and regulators generally expect to see both in trials of wake-promoting treatments.
Common definitions include change from baseline in the total score, the proportion of participants whose score falls to 10 or below (the normal range), or a fixed-point reduction. Choose the definition before the study starts, write it into the statistical analysis plan, and make sure your eligibility criterion (for example ESS of 11 or more at screening) leaves room for improvement to be observed.
In sleep apnoea trials, daytime sleepiness depends heavily on how much the participant actually uses their device or treatment. Record adherence alongside the ESS at every assessment, whether from device downloads entered on a site form or from a short participant diary, so the analysis can account for it. See EDC for wearable device studies for device-derived data.
Before go-live
Licence through Mapi Research Trust; record number, holder and expiry on the form.
Use the licensed item wording and translations; do not paraphrase situations.
A missing item makes the total invalid.
If the ESS is an inclusion criterion, add a range check that flags scores below it.
Record treatment or device use at the same visits as the ESS.
No more often than every few weeks, matching the "recent times" recall.
Eight situations are each rated 0 to 3 for the chance of dozing, and the ratings are summed for a total of 0 to 24.
A total above 10 indicates excessive daytime sleepiness. Scores of 16 or more are generally considered severe.
The participant's usual way of life in recent times, rather than a fixed number of days.
No. It is copyrighted and licensed through Mapi Research Trust.
The ESS measures daytime sleepiness; the PSQI measures sleep quality over the past month. Many sleep trials use both.
Yes. It runs in the phone browser from a secure link, with no app to install.
Keep exploring
PSQI eCRF template
Sleep quality over the past month.
Insomnia Severity Index template
Insomnia severity in seven items.
Sleep diary template
Nightly sleep diary.
EDC for sleep disorder trials
Sleep studies end to end.
eCOA software
Licensed instruments with licence tracking.
EDC for wearable device studies
Sleep data from devices.
Build the ESS as an ePRO with licence tracking. Free sandbox, no credit card.