A Transdiagnostic Tool for Sleep Medicine
Sleep medicine depends on patient-reported outcome measures (PROMs) to complement clinical interviews and objective tests such as polysomnography. Yet the questionnaires available today have significant shortcomings. Many focus on isolated symptoms or single disorders, which limits their ability to capture the full complexity of sleep conditions that patients actually experience. Others remain poorly validated despite years of use.
An international consortium of researchers has now introduced the European Sleep Questionnaire (ESQ), a new generic, transdiagnostic PROM designed to address these gaps. Developed within the European Union-funded Sleep Revolution project, the ESQ aims to provide a comprehensive, standardized instrument that works across the full spectrum of sleep disorders.
What the European Sleep Questionnaire Is
The ESQ is a self-administered questionnaire prototype comprising 119 items organized into nine sections. It uses Likert-type scales to assess three dimensions of sleep-related experiences over the past month: symptom severity, frequency, and bothersomeness. An additional module is available for follow-up assessments, allowing clinicians to track changes over time.
The instrument has been translated into 17 languages and built as a digital platform from the outset, making it suitable for multicenter studies across Europe and beyond. Its design integrates elements from clinical interviews, aiming to streamline assessment while better reflecting the real-world phenotypes that patients present with.
The nine sections cover a broad range of sleep domains, though the exact section structure is undergoing refinement as the validation process continues. The goal is to capture not just one type of sleep problem but the overlapping and co-occurring difficulties that characterize real patient populations.
How the ESQ Was Developed
The ESQ was initiated within the Sleep Revolution project (European Commission Grant 965417), a large collaborative framework that brought together sleep research centers across Europe. The development followed an iterative, multi-stage process.
First, the research team conducted a comprehensive literature review of existing sleep questionnaires to identify gaps in coverage and validation. Expert input was gathered from a consortium of 24 co-authors representing 22 institutions across eight European countries. Importantly, the development also included patient input through a representative from the Dutch Sleep Apnea Patient Association, ensuring the instrument reflects what matters to people living with sleep disorders.
From this foundation, the team constructed a 119-item prototype organized into nine sections. The initial validation phase involved cognitive interviews and psychometric evaluation in patients with various sleep disorders. Cognitive interviews assess whether respondents interpret questions as intended, while psychometric evaluation tests reliability, validity, and other measurement properties.
The lead author is Dirk A. Pevernagie of Ghent University in Belgium. The co-author list includes leading sleep researchers from institutions such as Reykjavik University (Iceland), Gothenburg University and Sahlgrenska University Hospital (Sweden), Radboud University Medical Center and Leiden University Medical Centre (Netherlands), University College Dublin (Ireland), the University of Freiburg (Germany), and the University of Eastern Finland.
Why It Matters
Existing sleep questionnaires tend to be disorder-specific. The Insomnia Severity Index, for example, assesses insomnia symptoms but captures nothing about sleep-disordered breathing, circadian rhythm disorders, or hypersomnia. The STOP-Bang screens for obstructive sleep apnea but does not evaluate insomnia or restless legs syndrome. A patient with comorbid insomnia and sleep apnea would need multiple instruments, each with different scoring systems and recall periods.
The ESQ is designed to change this. As a single, transdiagnostic instrument, it can capture the full clinical picture in one administration. This is particularly important because sleep disorders frequently co-occur. Insomnia and obstructive sleep apnea coexist in a condition known as COMISA, which affects a substantial proportion of sleep clinic patients. Restless legs syndrome overlaps with insomnia. Circadian rhythm disorders can masquerade as or exacerbate other sleep problems.
A transdiagnostic PROM also supports personalized medicine. By assessing severity, frequency, and bothersomeness separately across multiple domains, the ESQ can generate a symptom profile unique to each patient. Clinicians can see not just whether a patient has poor sleep but where the greatest burden lies and which symptoms are most distressing.
The digital implementation and multilingual availability also matter for research. A single instrument available in 17 languages allows direct cross-country comparisons in multicenter trials, something that is difficult when each study site uses different locally validated questionnaires.
What Comes Next
The ESQ is still under development and has not yet been publicly released. The current prototype has undergone initial validation through cognitive interviews and psychometric evaluation, but further work remains.
The research team plans to continue item refinement, which will likely reduce the 119-item pool to a more practical length for clinical use. A scoring key needs to be created. Additional validation studies will test the instrument in larger and more diverse populations, including patients with sleep disorders not yet represented in the initial sample.
The developers also plan to extend the ESQ into specific populations and explore its use in preventive strategies, clinical practice, and personalized treatment appraisal. If the remaining validation steps are successful, the ESQ could become a standard tool in European sleep medicine, comparable in scope to widely used generic PROMs in other fields of medicine.
Funding for the project came from the European Commission (Grant 965417), with additional support from Ghent University (BOFBAF2024071501) and the Swedish Heart and Lung Foundation (ALFGBG1006211).
Source
Pevernagie DA, et al. The Development of the European Sleep Questionnaire (ESQ): A New Patient-Reported Outcome Measure. Journal of Sleep Research. 2026 Jul 20:e70401. PMID: 42473734. DOI: 10.1111/jsr.70401.