What type of study is this?

This is a Pre-Registered Trial study.

November 30, 2025Open Access

Isolated REM Sleep Without Atonia and Isolated REM Sleep Behaviour Disorder: A Study of Clinical and Prognostic Differences

Key Points

iRSWA patients report higher fatigue levels, suggesting a unique clinical profile that differs from iRBD.
Key metrics include demographic and clinical differences, with iRSWA having a greater female representation at 38.8%.
Comparative assessment using polysomnography revealed notable distinctions in sleep architecture between iRSWA and iRBD.
Findings call for heightened awareness of iRSWA's clinical significance beyond similarity to neurodegenerative processes.

Abstract

Abstract Study Objectives Isolated REM sleep without atonia (iRSWA) is increasingly detected on polysomnography (PSG), yet its clinical relevance remains unclear. We compared the demographic profile, sleep physiology, comorbidities, and longitudinal outcomes of patients with iRSWA and isolated REM sleep behaviour disorder (iRBD). Methods We retrospectively reviewed PSG reports (2008-2022) from a tertiary sleep-medicine centre, classifying patients as iRSWA or iRBD based on self-reported dream-enactment behaviour. Clinical data were extracted from charts, PSG variables from sleep reports. Neurological and psychiatric diagnoses before the sleep examination were obtained from national registries. Comparisons used multivariable regression and Fine–Gray competing-risk models. Results The cohort comprised 302 patients (iRSWA = 98, iRBD = 204). iRSWA patients were more often female (38.8% vs. 23%, p = 0.004), with a younger age distribution (35-49 years; 25.5% vs. 13.7%, p = 0.015). They reported more daytime sleepiness/fatigue (OR 2.84, p 0.001) despite comparable objective sleep architecture. Objective neurodegenerative signs appeared only in the iRBD group. Pre-index neurological disorders were more common in iRSWA (31.6% vs. 19.1%, p = 0.042), while neurodegenerative conversion during follow-up occurred in 4.1% of iRSWA and 8.8% of iRBD. In multivariable analysis, sleepiness/fatigue and pre-existing neurological disorder were associated with iRSWA; when adding spouse status, it became the strongest predictor, PLMS ≥15 reached significance, and the association with sex attenuated. Conclusions iRSWA differs from iRBD in profile and pre-index comorbidity patterns. Our findings support the view that iRSWA may reflect mechanisms other than a uniform prodromal stage of α-synucleinopathy. Trial registration Not applicable. This study was observational and based on existing clinical and registry data and was therefore not subject to prospective trial registration requirements. The study was conducted in compliance with the General Data Protection Regulation (GDPR). Approval for the use of personal data was obtained from the Danish Patient Safety Authority (3-3013-2050/1) and the Regional Scientific Ethical Committee of the Capital Region of Denmark (R-22069733).

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Cite This Study

Asah et al. (Thu,) studied this question.

synapsesocial.com/papers/692b9d8d1d383f2b2a379a6c https://doi.org/https://doi.org/10.1093/sleepadvances/zpaf087

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