Variation in Sleep Duration Across Latitudes and Countries: A Bayesian Hierarchical Analysis of Wearable Data

Variation in Sleep Duration Across Latitudes and Countries: A Bayesian Hierarchical Analysis of Wearable Data | 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 Article Variation in Sleep Duration Across Latitudes and Countries: A Bayesian Hierarchical Analysis of Wearable Data Faraaz Akhtar, Alistair Brownlee, Cameron Crawford This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8533421/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract Seasonal effects on sleep have been documented but remain poorly characterised at a global scale. Using wearable-derived data from 697 individuals contributing 185143 nights across 49 countries, we examined how sleep duration varies with season, day length, latitude, and country using Bayesian hierarchical models. Across the dataset, sleep duration decreased with increasing day length, with a reduction of roughly 4.4 minutes per additional hour of daylight. In contrast, categorical season indicators contributed little explanatory power once individual- and country-level differences were modelled, suggesting that coarse season labels do not capture consistent structure in globally distributed samples. We found limited evidence that photoperiod sensitivity scales with latitude, despite large differences in seasonal light amplitude. At the same time, country-level variability emerged in both baseline sleep duration and estimated photoperiod responses. These findings indicate that global variation in sleep duration is shaped more strongly by individual and national differences than by calendar season. Biological sciences/Ecology Earth and environmental sciences/Ecology Health sciences/Medical research Full Text Additional Declarations Competing interest reported. The authors are employees of Terra API, which provides the wearable data infrastructure used in this study. Supplementary Files Supplementary.pdf Cite Share Download PDF Status: Posted 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. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. 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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-8533421","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Article","associatedPublications":[],"authors":[{"id":570920448,"identity":"ae82be44-dfa4-4843-bc43-81f9037eae2e","order_by":0,"name":"Faraaz Akhtar","email":"data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAZAAAAAyAQMAAABI0h/eAAAABlBMVEX///8AAABVwtN+AAAACXBIWXMAAA7EAAAOxAGVKw4bAAAAyklEQVRIiWNgGAWjYBAC9gYwZUOCFp4DYCpNgoGBmTQth0nRwn724Ycff87Xmc/IP/i4co8dA397AwEtPOnGkj08tyVkbiQzG555lswgceYAfi32DGkMEjwStyUkJJLZJBsOMDMYSCQQsIX/GfPPPwbnQFrYfzYcqCdCi0QamzRPwgGwLYwNBw4To+UZm7XMgWTJGTyPjYEOO85D0C88/GnMN9/8seOXYE98+LHhQLUcwRBDAAGIe3iIVQ8E/ATcMwpGwSgYBSMXAAAetzqrQ98g0QAAAABJRU5ErkJggg==","orcid":"","institution":"Terra API","correspondingAuthor":true,"prefix":"","firstName":"Faraaz","middleName":"","lastName":"Akhtar","suffix":""},{"id":570920449,"identity":"b440e22e-198c-4a08-8162-4122b7fa740b","order_by":1,"name":"Alistair Brownlee","email":"","orcid":"","institution":"Terra API","correspondingAuthor":false,"prefix":"","firstName":"Alistair","middleName":"","lastName":"Brownlee","suffix":""},{"id":570920450,"identity":"e625fbc3-eb7f-4c90-a78d-e4a7d9f1bf89","order_by":2,"name":"Cameron Crawford","email":"","orcid":"","institution":"Terra API","correspondingAuthor":false,"prefix":"","firstName":"Cameron","middleName":"","lastName":"Crawford","suffix":""}],"badges":[],"createdAt":"2026-01-06 16:23:30","currentVersionCode":1,"declarations":"","doi":"10.21203/rs.3.rs-8533421/v1","doiUrl":"https://doi.org/10.21203/rs.3.rs-8533421/v1","draftVersion":[],"editorialEvents":[],"editorialNote":"","failedWorkflow":false,"files":[{"id":99748373,"identity":"a99014ac-4394-4a01-bc12-b2c8a9206fa9","added_by":"auto","created_at":"2026-01-08 03:03:39","extension":"json","order_by":0,"title":"","display":"","copyAsset":false,"role":"acdc-reference","size":5295,"visible":true,"origin":"","legend":"","description":"","filename":"34b2cce2c08a4e69bcb449c5ac816f40.json","url":"https://assets-eu.researchsquare.com/files/rs-8533421/v1/ce2bbee2132ed569d30c0564.json"},{"id":100360112,"identity":"de0b0409-372f-4569-ab21-e8079c7b4c1e","added_by":"auto","created_at":"2026-01-16 07:37:24","extension":"pdf","order_by":1,"title":"","display":"","copyAsset":false,"role":"manuscript-pdf","size":1294071,"visible":true,"origin":"","legend":"","description":"","filename":"seasonsleepv2.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8533421/v1_covered_a9fd2cc8-3ddd-405c-85b0-cd6c6032a53b.pdf"},{"id":99748374,"identity":"17d2c310-47d1-4949-8fbe-ff6aff9af432","added_by":"auto","created_at":"2026-01-08 03:03:39","extension":"pdf","order_by":0,"title":"","display":"","copyAsset":false,"role":"supplement","size":451194,"visible":true,"origin":"","legend":"","description":"","filename":"Supplementary.pdf","url":"https://assets-eu.researchsquare.com/files/rs-8533421/v1/ec9e6a35cf80aed054d478ef.pdf"}],"financialInterests":"Competing interest reported. 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