REM sleep drives cerebrospinal fluid efflux through massive mechanical and vascular surges

REM sleep drives cerebrospinal fluid efflux through massive mechanical and vascular surges | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Biological Sciences - Article REM sleep drives cerebrospinal fluid efflux through massive mechanical and vascular surges Nicolas Zucker, Isabella Hurvitz, Alexandre Dizeux, Marta Matei, and 5 more This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8335499/v1 This work is licensed under a CC BY 4.0 License Status: Under Review Version 1 posted You are reading this latest preprint version Abstract The glymphatic system clears metabolic waste through cerebrospinal fluid (CSF) transport in the brain parenchyma and is most active during sleep. Yet the physical mechanisms generating glymphatic flow remain unclear, particularly the contribution of rapid eye movement (REM) sleep. Reports of reduced CSF inflow during REM have suggested a minimal role, yet imaging methods have, to date, been unable to capture whole-brain, multiparametric brain dynamics across full sleep cycles. Here, we develop an original multiparametric functional imaging modality using ultrasound during natural sleep in rodents. Our approach simultaneously maps brain mechanical properties, vascular activity, morphological deformations and intraventricular CSF flow at high spatiotemporal resolution. We show that REM onset is marked by a rapid decrease in cortical and midbrain stiffness—indicative of extracellular fluid expansion—followed approximately fifteen seconds later by a large and sustained increase in cerebral blood volume and mesoscale tissue deformation during the full REM episode. These vascular and mechanical surges coincide with elevated CSF efflux through the cerebral aqueduct and ventricles. REM-associated dynamics far exceed cardiac and respiratory pulsations in generating tissue strain and CSF motion. Complementary to NREM sleep which has been shown to promote CSF inflow via perivascular pathways, our results show that REM sleep strongly drives efflux through vascular–mechanical coupling. By enabling simultaneous imaging of brain stiffness, mesoscopic strain, vascular activity and intraventricular CSF flow, multiparametric functional ultrasound imaging uncovers REM sleep as a pivotal biomechanical phase of brain clearance. Biological sciences/Neuroscience/Circadian rhythms and sleep/REM sleep Biological sciences/Biological techniques/Imaging/Ultrasound Full Text Additional Declarations Yes there is potential Competing Interest. MT and TD are co-founders and shareholders of Iconeus and have received funding from Iconeus for research on functional ultrasound imaging. Some of their patents are licensed to Iconeus company. MT, and TD are members of the scientific board of Iconeus company. TD is consultant for Iconeus Company. NZ has patents with the Iconeus company. Supplementary Files VFSupplementaryVideo1.mov Supplementary Video 1 VFSupplementaryVideo2.mp4 Supplementary Video 2 VFSupplementaryVideo3.mp4 Supplementary Video 3 VFSupplementaryVideo4.avi Supplementary Video 4 VFSupplementaryVideo5.avi Supplementary Video 5 VFSupplementaryVideo6.avi Supplementary Video 6 VFSupplementaryVideo7.avi Supplementary Video 7 Cite Share Download PDF Status: Under Review Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. 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Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8335499","acceptedTermsAndConditions":true,"allowDirectSubmit":false,"archivedVersions":[],"articleType":"Biological Sciences - Article","associatedPublications":[],"authors":[{"id":590532923,"identity":"77d3f617-e5b5-4d16-9cc2-7494fd4b8486","order_by":0,"name":"Nicolas Zucker","email":"","orcid":"https://orcid.org/0009-0005-6332-9094","institution":"Inserm, ESPCI Paris, CNRS, PSL University","correspondingAuthor":false,"prefix":"","firstName":"Nicolas","middleName":"","lastName":"Zucker","suffix":""},{"id":590532924,"identity":"5df16cff-cf87-4a94-b3d1-ebec896f8538","order_by":1,"name":"Isabella 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NZ has patents with the Iconeus company.","formattedTitle":"REM sleep drives cerebrospinal fluid efflux through massive mechanical and vascular surges","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":true,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"nature-portfolio","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"","title":"Nature Portfolio","twitterHandle":"","acdcEnabled":false,"dfaEnabled":false,"editorialSystem":"ejp","reportingPortfolio":"","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"","lastPublishedDoi":"10.21203/rs.3.rs-8335499/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8335499/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"The glymphatic system clears metabolic waste through cerebrospinal fluid (CSF) transport in the brain parenchyma and is most active during sleep. Yet the physical mechanisms generating glymphatic flow remain unclear, particularly the contribution of rapid eye movement (REM) sleep. Reports of reduced CSF inflow during REM have suggested a minimal role, yet imaging methods have, to date, been unable to capture whole-brain, multiparametric brain dynamics across full sleep cycles. Here, we develop an original multiparametric functional imaging modality using ultrasound during natural sleep in rodents. Our approach simultaneously maps brain mechanical properties, vascular activity, morphological deformations and intraventricular CSF flow at high spatiotemporal resolution. We show that REM onset is marked by a rapid decrease in cortical and midbrain stiffness—indicative of extracellular fluid expansion—followed approximately fifteen seconds later by a large and sustained increase in cerebral blood volume and mesoscale tissue deformation during the full REM episode. These vascular and mechanical surges coincide with elevated CSF efflux through the cerebral aqueduct and ventricles. REM-associated dynamics far exceed cardiac and respiratory pulsations in generating tissue strain and CSF motion. Complementary to NREM sleep which has been shown to promote CSF inflow via perivascular pathways, our results show that REM sleep strongly drives efflux through vascular–mechanical coupling. By enabling simultaneous imaging of brain stiffness, mesoscopic strain, vascular activity and intraventricular CSF flow, multiparametric functional ultrasound imaging uncovers REM sleep as a pivotal biomechanical phase of brain clearance.","manuscriptTitle":"REM sleep drives cerebrospinal fluid efflux through massive mechanical and vascular surges","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-03-03 04:28:10","doi":"10.21203/rs.3.rs-8335499/v1","editorialEvents":[],"status":"published","journal":{"display":false,"email":"[email protected]","identity":"nature","isNatureJournal":true,"hasQc":false,"allowDirectSubmit":false,"externalIdentity":"nature","sideBox":"Learn more about [Nature](http://www.nature.com/nature/)","snPcode":"","submissionUrl":"","title":"Nature","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"ejp","reportingPortfolio":"Nature","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"94b5aa8b-bb14-4f4e-855e-22abc43cf0aa","owner":[],"postedDate":"March 3rd, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"under-review","subjectAreas":[{"id":62842076,"name":"Biological sciences/Neuroscience/Circadian rhythms and sleep/REM sleep"},{"id":62842077,"name":"Biological sciences/Biological techniques/Imaging/Ultrasound"}],"tags":[],"updatedAt":"2026-05-08T18:30:18+00:00","versionOfRecord":[],"versionCreatedAt":"2026-03-03 04:28:10","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8335499","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8335499","identity":"rs-8335499","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}