{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,29]],"date-time":"2026-08-29T07:09:12Z","timestamp":1787987352952,"version":"build-2784847793"},"reference-count":46,"publisher":"MDPI AG","issue":"15","license":[{"start":{"date-parts":[[2022,7,22]],"date-time":"2022-07-22T00:00:00Z","timestamp":1658448000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministry of Health &amp; Welfare","award":["HI22C0467"],"award-info":[{"award-number":["HI22C0467"]}]},{"name":"Ministry of Health &amp; Welfare","award":["2017R1A5A1014708"],"award-info":[{"award-number":["2017R1A5A1014708"]}]},{"name":"Ministry of Science and ICT","award":["HI22C0467"],"award-info":[{"award-number":["HI22C0467"]}]},{"name":"Ministry of Science and ICT","award":["2017R1A5A1014708"],"award-info":[{"award-number":["2017R1A5A1014708"]}]},{"name":"2022 Joint Research Project of Institutes of Science and Technology","award":["HI22C0467"],"award-info":[{"award-number":["HI22C0467"]}]},{"name":"2022 Joint Research Project of Institutes of Science and Technology","award":["2017R1A5A1014708"],"award-info":[{"award-number":["2017R1A5A1014708"]}]},{"name":"GIST Research Institute (GRI)","award":["HI22C0467"],"award-info":[{"award-number":["HI22C0467"]}]},{"name":"GIST Research Institute (GRI)","award":["2017R1A5A1014708"],"award-info":[{"award-number":["2017R1A5A1014708"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nutrients"],"abstract":"<jats:p>Vitamin D deficiency is prevalent in many developed countries, and several studies suggest that vitamin D plays an essential role in brain function. A recent study showed that vitamin D deficiency was closely associated with daytime sleepiness and shorter sleep time. The relationshipbetween vitamin D levels and calcium levels is well established, and calcium level regulates slow-wave sleep generation. It is conceivable that the sleep disturbance in vitamin D deficiency may be due to an altered calcium level. Nonetheless, calcium levels, sleep disturbances, and activity rhythms have not been investigated directly. Therefore, we hypothesized that calcium and vitamin D levels might be important in regulating sleep and activity rhythm, and we analyzed the correlation with calcium levels by actigraphy analysis. Interestingly, a negative correlation was found between calcium level and sleep latency, total sleep time, use of sleep medicine, and daytime dysfunction among shift workers. In contrast, non-shift workers showed a negative correlation between the calcium level and the circadian phase. These findings suggest that low serum calcium levels may disrupt sleep\u2013wake control and rest\u2013activity rhythm, even if they are within the normal range.<\/jats:p>","DOI":"10.3390\/nu14153021","type":"journal-article","created":{"date-parts":[[2022,7,25]],"date-time":"2022-07-25T01:42:13Z","timestamp":1658713333000},"page":"3021","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":24,"title":["Lower Serum Calcium Levels Associated with Disrupted Sleep and Rest\u2013Activity Rhythm in Shift Workers"],"prefix":"10.3390","volume":"14","author":[{"given":"Yi-Seon","family":"Jeon","sequence":"first","affiliation":[{"name":"Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea"},{"name":"Current affiliation: Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Seungyeong","family":"Yu","sequence":"additional","affiliation":[{"name":"Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chaeyeon","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hyuk Joo","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Public Medical Service, Seoul National University Bundang Hospital, Seongnam 13620, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"In-Young","family":"Yoon","sequence":"additional","affiliation":[{"name":"Department of Psychiatry, Seoul National University Bundang Hospital, Seongnam 13620, Korea"},{"name":"Department of Psychiatry, Seoul National University College of Medicine, Seoul 03080, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0201-5401","authenticated-orcid":false,"given":"Tae","family":"Kim","sequence":"additional","affiliation":[{"name":"Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju 61005, Korea"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2022,7,22]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"292","DOI":"10.1016\/j.patbio.2014.08.001","article-title":"Impacts of shift work on sleep and circadian rhythms","volume":"62","author":"Boivin","year":"2014","journal-title":"Pathol. 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