{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,5]],"date-time":"2026-06-05T11:06:35Z","timestamp":1780657595781,"version":"3.54.1"},"reference-count":39,"publisher":"MDPI AG","issue":"22","license":[{"start":{"date-parts":[[2023,11,9]],"date-time":"2023-11-09T00:00:00Z","timestamp":1699488000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100002428","name":"FWF, Austrian Science Fund","doi-asserted-by":"publisher","award":["W 1233-B"],"award-info":[{"award-number":["W 1233-B"]}],"id":[{"id":"10.13039\/501100002428","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100002428","name":"FWF, Austrian Science Fund","doi-asserted-by":"publisher","award":["20102-F2002176-FPR"],"award-info":[{"award-number":["20102-F2002176-FPR"]}],"id":[{"id":"10.13039\/501100002428","id-type":"DOI","asserted-by":"publisher"}]},{"name":"county of Salzburg. Open Access Funding by the Austrian Science Fund","award":["W 1233-B"],"award-info":[{"award-number":["W 1233-B"]}]},{"name":"county of Salzburg. Open Access Funding by the Austrian Science Fund","award":["20102-F2002176-FPR"],"award-info":[{"award-number":["20102-F2002176-FPR"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>More and more people quantify their sleep using wearables and are becoming obsessed in their pursuit of optimal sleep (\u201corthosomnia\u201d). However, it is criticized that many of these wearables are giving inaccurate feedback and can even lead to negative daytime consequences. Acknowledging these facts, we here optimize our previously suggested sleep classification procedure in a new sample of 136 self-reported poor sleepers to minimize erroneous classification during ambulatory sleep sensing. Firstly, we introduce an advanced interbeat-interval (IBI) quality control using a random forest method to account for wearable recordings in naturalistic and more noisy settings. We further aim to improve sleep classification by opting for a loss function model instead of the overall epoch-by-epoch accuracy to avoid model biases towards the majority class (i.e., \u201clight sleep\u201d). Using these implementations, we compare the classification performance between the optimized (loss function model) and the accuracy model. We use signals derived from PSG, one-channel ECG, and two consumer wearables: the ECG breast belt Polar\u00ae H10 (H10) and the Polar\u00ae Verity Sense (VS), an optical Photoplethysmography (PPG) heart-rate sensor. The results reveal a high overall accuracy for the loss function in ECG (86.3 %, \u03ba = 0.79), as well as the H10 (84.4%, \u03ba = 0.76), and VS (84.2%, \u03ba = 0.75) sensors, with improvements in deep sleep and wake. In addition, the new optimized model displays moderate to high correlations and agreement with PSG on primary sleep parameters, while measures of reliability, expressed in intra-class correlations, suggest excellent reliability for most sleep parameters. Finally, it is demonstrated that the new model is still classifying sleep accurately in 4-classes in users taking heart-affecting and\/or psychoactive medication, which can be considered a prerequisite in older individuals with or without common disorders. Further improving and validating automatic sleep stage classification algorithms based on signals from affordable wearables may resolve existing scepticism and open the door for such approaches in clinical practice.<\/jats:p>","DOI":"10.3390\/s23229077","type":"journal-article","created":{"date-parts":[[2023,11,9]],"date-time":"2023-11-09T10:19:27Z","timestamp":1699525167000},"page":"9077","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":13,"title":["From Pulses to Sleep Stages: Towards Optimized Sleep Classification Using Heart-Rate Variability"],"prefix":"10.3390","volume":"23","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6235-060X","authenticated-orcid":false,"given":"Pavlos I.","family":"Topalidis","sequence":"first","affiliation":[{"name":"Laboratory for Sleep, Cognition and Consciousness Research, Department of Psychology, Centre for Cognitive Neuroscience Salzburg (CCNS), Paris-Lodron University of Salzburg, 5020 Salzburg, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2747-7728","authenticated-orcid":false,"given":"Sebastian","family":"Baron","sequence":"additional","affiliation":[{"name":"Department of Mathematics, Paris-Lodron University of Salzburg, 5020 Salzburg, Austria"},{"name":"Department of Artificial Intelligence and Human Interfaces (AIHI), Paris-Lodron University of Salzburg, 5020 Salzburg, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7977-8557","authenticated-orcid":false,"given":"Dominik P. J.","family":"Heib","sequence":"additional","affiliation":[{"name":"Laboratory for Sleep, Cognition and Consciousness Research, Department of Psychology, Centre for Cognitive Neuroscience Salzburg (CCNS), Paris-Lodron University of Salzburg, 5020 Salzburg, Austria"},{"name":"Institut Proschlaf, 5020 Salzburg, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0018-7632","authenticated-orcid":false,"given":"Esther-Sevil","family":"Eigl","sequence":"additional","affiliation":[{"name":"Laboratory for Sleep, Cognition and Consciousness Research, Department of Psychology, Centre for Cognitive Neuroscience Salzburg (CCNS), Paris-Lodron University of Salzburg, 5020 Salzburg, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5043-9909","authenticated-orcid":false,"given":"Alexandra","family":"Hinterberger","sequence":"additional","affiliation":[{"name":"Laboratory for Sleep, Cognition and Consciousness Research, Department of Psychology, Centre for Cognitive Neuroscience Salzburg (CCNS), Paris-Lodron University of Salzburg, 5020 Salzburg, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-5899-8772","authenticated-orcid":false,"given":"Manuel","family":"Schabus","sequence":"additional","affiliation":[{"name":"Laboratory for Sleep, Cognition and Consciousness Research, Department of Psychology, Centre for Cognitive Neuroscience Salzburg (CCNS), Paris-Lodron University of Salzburg, 5020 Salzburg, Austria"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2023,11,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"2115","DOI":"10.5664\/jcsm.9476","article-title":"Sleep is essential to health: An American Academy of Sleep Medicine position statement","volume":"17","author":"Ramar","year":"2021","journal-title":"J. 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