{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:10:40Z","timestamp":1760235040278,"version":"build-2065373602"},"reference-count":34,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2021,7,14]],"date-time":"2021-07-14T00:00:00Z","timestamp":1626220800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>This paper evaluates variations in solar activity and their impact on the human nervous system, including the manner in which human behavior and decision-making reflect such effects in the context of (symmetrical) social interactions. The relevant research showed that solar activity, manifesting itself through the exposure of the Earth to charged particles from the Sun, affects heart variability. The evaluation methods focused on examining the relationships between selected psychophysiological data and solar activity, which generally causes major alterations in the low-level electromagnetic field. The investigation within this paper revealed that low-level EMF changes are among the factors affecting heart rate variability and, thus, also variations at the spectral level of the rate, in the VLF, (f = 0.01\u20130.04 Hz), LF (f = 0.04\u20130.15 Hz), and HF (f = 0.15 a\u017e 0.40 Hz) bands. The results of the presented experiments can also be interpreted as an indirect explanation of sudden deaths and heart failures.<\/jats:p>","DOI":"10.3390\/s21144817","type":"journal-article","created":{"date-parts":[[2021,7,14]],"date-time":"2021-07-14T21:56:51Z","timestamp":1626299811000},"page":"4817","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Methods and Experiments for Sensing Variations in Solar Activity and Defining Their Impact on Heart Variability"],"prefix":"10.3390","volume":"21","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-6653-617X","authenticated-orcid":false,"given":"Michael","family":"Hanzelka","sequence":"first","affiliation":[{"name":"Department of Theoretical and Experimental Electrical Engineering, Brno University of Technology, 616 00 Brno, Czech Republic"}]},{"given":"Ji\u0159\u00ed","family":"Dan","sequence":"additional","affiliation":[{"name":"Department of Psychology, Faculty of Arts and Letter, Catholic University in Ru\u017eomberok, 034 01 Ru\u017eomberok, Slovakia"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0089-262X","authenticated-orcid":false,"given":"Zolt\u00e1n","family":"Szab\u00f3","sequence":"additional","affiliation":[{"name":"Department of Theoretical and Experimental Electrical Engineering, Brno University of Technology, 616 00 Brno, Czech Republic"}]},{"given":"Zden\u011bk","family":"Roubal","sequence":"additional","affiliation":[{"name":"Department of Theoretical and Experimental Electrical Engineering, Brno University of Technology, 616 00 Brno, Czech Republic"}]},{"given":"P\u0159emysl","family":"Dohnal","sequence":"additional","affiliation":[{"name":"Department of Theoretical and Experimental Electrical Engineering, Brno University of Technology, 616 00 Brno, Czech Republic"}]},{"given":"Radim","family":"Kadlec","sequence":"additional","affiliation":[{"name":"Department of Theoretical and Experimental Electrical Engineering, Brno University of Technology, 616 00 Brno, Czech Republic"}]}],"member":"1968","published-online":{"date-parts":[[2021,7,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Surkov, V.M.H. 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