{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T06:04:45Z","timestamp":1790229885977,"version":"4.1.0"},"reference-count":30,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T00:00:00Z","timestamp":1790208000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003562","name":"Ministry of Environment","doi-asserted-by":"publisher","id":[{"id":"10.13039\/501100003562","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Public Health"],"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Previous studies have shown inconsistent associations between sleep duration and height gain in early childhood. The relationships of bedtime and nighttime awakenings with growth remain unclear. We investigated whether sleep characteristics at 1.5\u202fyears were associated with subsequent height gain.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Forty-nine thousand two hundred eight singleton, term toddlers classified as appropriate for gestational age were selected from the Japan Environment and Children\u2019s Study. Nighttime sleep was defined as sleep between 20:00 and 07:59. Nighttime sleep duration, bedtime, and nighttime awakenings were categorized as long (\u226510\u202fh) or short (&amp;lt;10\u202fh), early (20:00\u201321:59) or late (\u226522:00), and infrequent (&amp;lt;3) or frequent (\u22653), respectively. Linear mixed-effects models were used to examine associations with height and height standard deviation scores (SDS).<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      The early bedtime group showed greater monthly increases in height and height SDS than the late bedtime group, corresponding to 18-month differences of 0.13\u202fcm (\n                      <jats:italic>B<\/jats:italic>\n                      \u202f=\u202f7.21\u202f\u00d7\u202f10\n                      <jats:sup>\u2212<\/jats:sup>\n                      3\u202fcm\/month, 95% confidence interval (CI) 0.06 to 0.20;\n                      <jats:italic>p<\/jats:italic>\n                      \u202f&amp;lt;\u202f0.001) and 0.046 SD (\n                      <jats:italic>B<\/jats:italic>\n                      \u202f=\u202f2.53\u202f\u00d7\u202f10\n                      <jats:sup>\u2212<\/jats:sup>\n                      3 SD\/month, 95% CI 0.027 to 0.064;\n                      <jats:italic>p<\/jats:italic>\n                      \u202f&amp;lt;\u202f0.001), respectively. The long sleep group did not differ significantly from the short sleep group in either outcome in the primary multivariable model. In continuous analyses, sleep duration was significantly associated with height gain, but not with height SDS gain. In an additional analysis including sleep outside the predefined nighttime window, the &amp;gt;14-h group showed smaller increases in height and height SDS than the 11\u201314-h group, whereas the &amp;lt;11-h group did not differ significantly from the 11\u201314-h group. The infrequent nighttime awakenings group did not differ significantly from the frequent nighttime awakenings group in either outcome.\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Earlier bedtime at 1.5\u202fyears was associated with greater height gain, although the magnitude of the association was small. The associations of sleep duration with height gain varied between nighttime and 24-h sleep analyses. The observed association with earlier bedtime may have practical relevance because bedtime can be discussed during routine child health guidance; however, given the observational study design, these findings should not be interpreted as evidence of a causal effect.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fpubh.2026.1945746","type":"journal-article","created":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T05:44:43Z","timestamp":1790228683000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Earlier bedtime at 1.5\u202fyears is associated with greater height gain at 3\u202fyears of age: a nationwide birth cohort study of the Japan environment and children\u2019s study"],"prefix":"10.3389","volume":"14","author":[{"given":"Shintaro","family":"Senoo","sequence":"first","affiliation":[{"name":"Division of Pediatrics & Perinatology, Faculty of Medicine, Tottori University","place":["Yonago, Tottori, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Keita","family":"Shimizu","sequence":"additional","affiliation":[{"name":"Division of Pediatrics & Perinatology, Faculty of Medicine, Tottori University","place":["Yonago, Tottori, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Masanobu","family":"Fujimoto","sequence":"additional","affiliation":[{"name":"Division of Pediatrics & Perinatology, Faculty of Medicine, Tottori University","place":["Yonago, Tottori, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yukiko","family":"Yamaguchi","sequence":"additional","affiliation":[{"name":"Division of Pediatrics & Perinatology, Faculty of Medicine, Tottori University","place":["Yonago, Tottori, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hiroshi","family":"Sunada","sequence":"additional","affiliation":[{"name":"Advanced Medicine, Innovation and Clinical Research Center, Tottori University Hospital","place":["Yonago, Tottori, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Toshio","family":"Masumoto","sequence":"additional","affiliation":[{"name":"Division of Health Administration and Promotion, Faculty of Medicine, Tottori University","place":["Yonago, Tottori, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Akemi","family":"Morita","sequence":"additional","affiliation":[{"name":"Division of Health Administration and Promotion, Faculty of Medicine, Tottori University","place":["Yonago, Tottori, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Hisashi","family":"Noma","sequence":"additional","affiliation":[{"name":"Department of Interdisciplinary Statistical Mathematics, The Institute of Statistical Mathematics","place":["Tachikawa, Tokyo, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Noriyuki","family":"Namba","sequence":"additional","affiliation":[{"name":"Division of Pediatrics & Perinatology, Faculty of Medicine, Tottori University","place":["Yonago, Tottori, Japan"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"name":"on behalf of the Japan Environment Children's Study Group","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,9,24]]},"reference":[{"key":"ref1","doi-asserted-by":"publisher","first-page":"185","DOI":"10.1002\/sim.4780060210","article-title":"On the modelling of human growth","volume":"6","author":"Karlberg","year":"1987","journal-title":"Stat Med"},{"key":"ref2","doi-asserted-by":"publisher","first-page":"1281","DOI":"10.1016\/j.sleep.2015.07.006","article-title":"Sleep duration and growth outcomes across the first two years of life in the GUSTO study","volume":"16","author":"Zhou","year":"2015","journal-title":"Sleep 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