{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,16]],"date-time":"2026-04-16T07:14:09Z","timestamp":1776323649587,"version":"3.50.1"},"reference-count":48,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2015,3,13]],"date-time":"2015-03-13T00:00:00Z","timestamp":1426204800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>Two entropy-based approaches are investigated to study patterns describing differences in time intervals between consecutive heartbeats. The first method explores matrices arising from networks of transitions constructed following events represented by a time series. The second method considers distributions of ordinal patterns of length three, whereby patterns with repeated values are counted as different patterns. Both methods provide estimators of dynamical aspects of short-term heartbeat signals obtained from nocturnal Holter electrocardiogram (ECG) recordings of healthy people of different ages and genders. The deceleration capacity, arising from the adjacency matrix of the network, and the entropy rate, resulting from the transition matrix of the network, are also calculated, and both significantly decay with aging. As people age, the permutation entropy grows, due to the increase in patterns with repeated values. All of these estimators describe in a consistent way changes in the beat-to-beat heart period dynamics caused by aging. An overall slowing down of heart period changes is observed, and an increase of permutation entropy results from the progressive increase of patterns with repeated values. This result points to the sympathetic drive becoming dominant in cardiac regulation of nocturnal heart rate with age.<\/jats:p>","DOI":"10.3390\/e17031253","type":"journal-article","created":{"date-parts":[[2015,3,13]],"date-time":"2015-03-13T11:51:52Z","timestamp":1426247512000},"page":"1253-1272","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":20,"title":["Entropic Measures of Complexity of Short-Term Dynamics of Nocturnal Heartbeats in an Aging Population"],"prefix":"10.3390","volume":"17","author":[{"given":"Danuta","family":"Makowiec","sequence":"first","affiliation":[{"name":"Institute of Theoretical Physics and Astrophysics, University of Gda\u0144sk, 80-952 Gda\u0144sk, ul. Wita Stwosza 57, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Agnieszka","family":"Kaczkowska","sequence":"additional","affiliation":[{"name":"Faculty of Applied Physics and Mathematics, Gda\u0144sk University of Technology, 80-233 Gda\u0144sk, ul. Narutowicza 11\/12, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Dorota","family":"Wejer","sequence":"additional","affiliation":[{"name":"Institute of Theoretical Physics and Astrophysics, University of Gda\u0144sk, 80-952 Gda\u0144sk, ul. Wita Stwosza 57, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Marta","family":"\u017barczy\u0144ska-Buchowiecka","sequence":"additional","affiliation":[{"name":"Chair & Clinic of Cardiology, Medical University of Gda\u0144sk, 80-211 Gda\u0144sk, ul. D\u0229binki 7, Poland"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zbigniew","family":"Struzik","sequence":"additional","affiliation":[{"name":"Institute of Theoretical Physics and Astrophysics, University of Gda\u0144sk, 80-952 Gda\u0144sk, ul. Wita Stwosza 57, Poland"},{"name":"RIKEN Brain Science Institute, 2-1 Hirosawa, 351-0198 Wako-shi, Japan"},{"name":"Graduate School of Education, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, 113-0033 Tokyo, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2015,3,13]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1553","DOI":"10.3390\/e14081553","article-title":"Permutation entropy and its main biomedical and econophysics applications: A review","volume":"14","author":"Zanin","year":"2012","journal-title":"Entropy"},{"key":"ref_2","doi-asserted-by":"crossref","unstructured":"Faes, L., Nollo, G., Jurysta, F., and Marinazzo, D. 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