{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,15]],"date-time":"2026-10-15T11:48:14Z","timestamp":1792064894037,"version":"4.4.0"},"reference-count":45,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T00:00:00Z","timestamp":1789430400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"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>Sleep problems are common among college students and may involve daytime behavior, bedtime self-regulation, and irregular sleep timing. This study examined the associations of physical activity, bedtime procrastination, social jetlag, and chronotype with sleep quality, including indirect associations through bedtime procrastination and social jetlag and whether these varied by chronotype.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>This cross-sectional study included 1,058 college students from four provinces in eastern China. Physical activity, sleep quality, bedtime procrastination, social jetlag, and chronotype were assessed using the Physical Activity Rating Scale-3, Pittsburgh Sleep Quality Index (PSQI), Bedtime Procrastination Scale, selected sleep-timing items from the Munich Chronotype Questionnaire, and five-item Morningness\u2013Eveningness Questionnaire, respectively. Correlation and regression analyses examined direct, indirect, and conditional associations.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      Physical activity was negatively correlated with PSQI scores (\n                      <jats:italic>r<\/jats:italic>\n                      = \u20130.383,\n                      <jats:italic>p<\/jats:italic>\n                      &amp;lt; 0.001), bedtime procrastination (\n                      <jats:italic>r<\/jats:italic>\n                      = \u20130.505,\n                      <jats:italic>p<\/jats:italic>\n                      &amp;lt; .001), and social jetlag (\n                      <jats:italic>r<\/jats:italic>\n                      = \u20130.420,\n                      <jats:italic>p<\/jats:italic>\n                      &amp;lt; 0.001). After adjustment for covariates and other model variables, physical activity remained negatively associated with PSQI scores (B = \u22120.014,\n                      <jats:italic>p<\/jats:italic>\n                      = 0.003). The indirect association through bedtime procrastination was negative [B = \u22120.017, 95% bootstrap CI (\u22120.023, \u22120.011)]. The indirect association through social jetlag was negative at more evening-oriented and mean chronotype scores (B = \u22120.017 and \u22120.005, respectively) but positive at a more morning-oriented score (B = 0.007). The serial indirect association through bedtime procrastination and social jetlag showed the same pattern (B = \u22120.023, \u22120.007, and 0.009, respectively).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusion<\/jats:title>\n                    <jats:p>Higher physical activity was directly associated with lower PSQI scores and indirectly associated with PSQI scores through less bedtime procrastination. Indirect associations involving social jetlag depended on chronotype, being negative at more evening-oriented and mean chronotype scores but reversing at a more morning-oriented score. These findings highlight the joint relevance of physical activity, bedtime regulation, sleep-timing regularity, and chronotype to sleep quality. Because the study was cross-sectional, the observed associations should not be interpreted as temporal or causal effects.<\/jats:p>\n                  <\/jats:sec>","DOI":"10.3389\/fpubh.2026.1949891","type":"journal-article","created":{"date-parts":[[2026,9,15]],"date-time":"2026-09-15T04:26:30Z","timestamp":1789446390000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["Physical activity and sleep quality among college students: a cross-sectional analysis of bedtime procrastination, social jetlag, and chronotype"],"prefix":"10.3389","volume":"14","author":[{"given":"Jiameng","family":"Sun","sequence":"first","affiliation":[{"name":"Institute of Physical Education, Nantong Normal College","place":["Nantong, China"]},{"name":"Faculty of Education, Universiti Kebangsaan Malaysia","place":["Bangi, Selangor, 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