{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T04:46:33Z","timestamp":1785818793538,"version":"3.56.0"},"reference-count":33,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T00:00:00Z","timestamp":1785801600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Sleep"],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Quantitative REM sleep without atonia (RSWA) metrics are increasingly used to characterize isolated REM sleep behavior disorder (iRBD) and as candidate biomarkers. Cohort follow-up often reports rising RSWA, but within-individual trajectories, particularly when tonic and phasic components diverge, remain sparsely documented.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>A man in his mid-seventies with iRBD underwent four attended video-polysomnograms over \u22126.5 years. Submental EMG was quantified using a REM sleep atonia index (RAI) with pre-specified exclusion of REM mini-epochs contaminated by artifact or physiological activation (arousal-linked activation and respiratory-event adjacency). Tonic and phasic submental RSWA components were extracted concurrently. Diary-anchored interviews around each visit captured enactment frequency, ordinal ratings of dream vividness\/recall and sleep-related accidental harm.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Corrected RAI varied non-monotonically (0.268, 0.401, 0.313, 0.463). Tonic and phasic RSWA dissociated: tonic activity declined overall, whereas phasic activity rose early and remained elevated. PSG-night enactment frequency tracked REM sleep opportunity (Spearman \u03c1 = 0.89;\n                      <jats:italic>n<\/jats:italic>\n                      = 4) more closely than corrected RAI or tonic\/phasic indices. Sleep-related harm was absent at the final visit despite persistent phasic activity.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>In this case, longitudinal RSWA did not behave as a single monotone scalar. Component-wise reporting alongside explicit REM sleep opportunity and exclusion accounting may be essential for interpreting apparent longitudinal change and relating electrophysiology to behavioral expression.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/frsle.2026.1816079","type":"journal-article","created":{"date-parts":[[2026,8,4]],"date-time":"2026-08-04T04:27:57Z","timestamp":1785817677000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Case Report: non-monotonic longitudinal RSWA with tonic\u2013phasic dissociation across serial attended video-polysomnography in isolated REM sleep behaviour disorder"],"prefix":"10.3389","volume":"5","author":[{"given":"Valentina","family":"Gnoni","sequence":"first","affiliation":[{"name":"Sleep Disorders Centre, Guy's and St Thomas' NHS Foundation Trust","place":["London, United Kingdom"]},{"name":"Sleep and Brain Plasticity Centre, Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London","place":["London, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Nazanin","family":"Biabani","sequence":"additional","affiliation":[{"name":"Sleep and Brain Plasticity Centre, Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London","place":["London, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Istvan","family":"Papp","sequence":"additional","affiliation":[{"name":"Sleep and Brain Plasticity Centre, Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London","place":["London, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Camilla","family":"Speicher","sequence":"additional","affiliation":[{"name":"Sleep and Brain Plasticity Centre, Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London","place":["London, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Adam","family":"Birdseye","sequence":"additional","affiliation":[{"name":"Sleep Disorders Centre, Guy's and St Thomas' NHS Foundation Trust","place":["London, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sakina","family":"Dastagir","sequence":"additional","affiliation":[{"name":"Sleep Disorders Centre, Guy's and St Thomas' NHS Foundation Trust","place":["London, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Martina","family":"Mulas","sequence":"additional","affiliation":[{"name":"Sleep Disorder Research Center and Neurology Unit, Department of Medical Sciences and Public Health, University of Cagliari","place":["Monserrato, Cagliari, Italy"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Monica","family":"Puligheddu","sequence":"additional","affiliation":[{"name":"Sleep Disorder Research Center and Neurology Unit, Department of Medical Sciences and Public Health, University of Cagliari","place":["Monserrato, Cagliari, Italy"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Clive","family":"Ballard","sequence":"additional","affiliation":[{"name":"Clinical and Biomedical Sciences, Faculty of Health and Life Sciences, University of Exeter","place":["Exeter, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Luigi","family":"Ferini-Strambi","sequence":"additional","affiliation":[{"name":"IRCCS San Raffaele Scientific Institute and University Vita-Salute San Raffaele","place":["Milan, Italy"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David","family":"O'Regan","sequence":"additional","affiliation":[{"name":"Sleep Disorders Centre, Guy's and St Thomas' NHS Foundation Trust","place":["London, United Kingdom"]},{"name":"Faculty of Life Science and Medicine, School of Basic and Medical Biosciences, King's College London","place":["London, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ivana","family":"Rosenzweig","sequence":"additional","affiliation":[{"name":"Sleep Disorders Centre, Guy's and St Thomas' NHS Foundation Trust","place":["London, United Kingdom"]},{"name":"Sleep and Brain Plasticity Centre, Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience (IoPPN), King's College London","place":["London, United Kingdom"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,8,4]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","first-page":"5391","DOI":"10.1113\/JP271324","article-title":"The anatomical, cellular and synaptic basis of motor atonia during rapid eye movement sleep","volume":"594","author":"Arrigoni","year":"2016","journal-title":"J. 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