{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,15]],"date-time":"2026-05-15T10:29:06Z","timestamp":1778840946008,"version":"3.51.4"},"reference-count":40,"publisher":"MDPI AG","issue":"19","license":[{"start":{"date-parts":[[2019,9,24]],"date-time":"2019-09-24T00:00:00Z","timestamp":1569283200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003725","name":"National Research Foundation of Korea","doi-asserted-by":"publisher","award":["2017R1A2B2004061"],"award-info":[{"award-number":["2017R1A2B2004061"]}],"id":[{"id":"10.13039\/501100003725","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Sleep plays a primary function for health and sustains physical and cognitive performance. Although various stimulation systems for enhancing sleep have been developed, they are difficult to use on a long-term basis. This paper proposes a novel stimulation system and confirms its feasibility for sleep. Specifically, in this study, a closed-loop vibration stimulation system that detects the heart rate (HR) and applies \u2212n% stimulus beats per minute (BPM) computed on the basis of the previous 5 min of HR data was developed. Ten subjects participated in the evaluation experiment, in which they took a nap for approximately 90 min. The experiment comprised one baseline and three stimulation conditions. HR variability analysis showed that the normalized low frequency (LF) and LF\/high frequency (HF) parameters significantly decreased compared to the baseline condition, while the normalized HF parameter significantly increased under the \u22123% stimulation condition. In addition, the HR density around the stimulus BPM significantly increased under the \u22123% stimulation condition. The results confirm that the proposed stimulation system could influence heart rhythm and stabilize the autonomic nervous system. This study thus provides a new stimulation approach to enhance the quality of sleep and has the potential for enhancing health levels through sleep manipulation.<\/jats:p>","DOI":"10.3390\/s19194136","type":"journal-article","created":{"date-parts":[[2019,9,25]],"date-time":"2019-09-25T03:51:18Z","timestamp":1569383478000},"page":"4136","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":15,"title":["Effect of Closed-Loop Vibration Stimulation on Heart Rhythm during Naps"],"prefix":"10.3390","volume":"19","author":[{"given":"Sang Ho","family":"Choi","sequence":"first","affiliation":[{"name":"Interdisciplinary Program in Bioengineering, Graduate School, Seoul National University, Seoul 03080, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Heenam","family":"Yoon","sequence":"additional","affiliation":[{"name":"Artificial Intelligence Laboratory, Software Center, LG Electronics, Seoul 06772, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hyung Won","family":"Jin","sequence":"additional","affiliation":[{"name":"Interdisciplinary Program in Bioengineering, Graduate School, Seoul National University, Seoul 03080, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Hyun Bin","family":"Kwon","sequence":"additional","affiliation":[{"name":"Interdisciplinary Program in Bioengineering, Graduate School, Seoul National University, Seoul 03080, Korea"},{"name":"Institute of Medical and Biological Engineering, Medical Research Center, Seoul National University, Seoul 03080, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Seong Min","family":"Oh","sequence":"additional","affiliation":[{"name":"Department of Neuropsychiatry and Center for Sleep and Chronobiology, Seoul National University Hospital, Seoul 03080, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yu Jin","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Neuropsychiatry and Center for Sleep and Chronobiology, Seoul National University Hospital, Seoul 03080, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Kwang Suk","family":"Park","sequence":"additional","affiliation":[{"name":"Institute of Medical and Biological Engineering, Medical Research Center, Seoul National University, Seoul 03080, Korea"},{"name":"Department of Biomedical Engineering, College of Medicine, Seoul National University, Seoul 03080, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2019,9,24]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"73","DOI":"10.1007\/s13534-018-0091-2","article-title":"Smart technologies toward sleep monitoring at home","volume":"9","author":"Park","year":"2019","journal-title":"Biomed. 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