title: Season of birth, sex and sleep timing preferences.
abstract: OBJECTIVE
  To evaluate whether the season of birth and sex are associated with preferences for bedtime among Chinese adults.
  
  
  METHODS
  A national population-based study on sleep preferences was conducted among Chinese in 2008. A questionnaire was used to collect information on the sleep time of Chinese adults. Analysis of covariance was used to examine the relationship between season of birth and preferences for bedtime. Two sets of potential confounders were used in the adjusted models. Model 1 adjusted for age. Model 2 additionally adjusted for area, occupation, education level, smoking, and drinking.
  
  
  METHODS
  The questionnaire was administered to a sample of 3959 Chinese adults.
  
  
  RESULTS
  Men had a higher delayed mean sleep onset and offset time (22:38 and 6:32) than women (22:18 and 6:25). Men also slept for a shorter duration compared to women (7 h 54 min vs. 8 h 7 min). Women born in fall had the latest sleep onset time sleep offset time (22:23/6:30), compared to their counterparts born in winter. These associations were attenuated by additional adjustments of more confounders.
  
  
  CONCLUSIONS
  There were significant differences in sleep timing preferences between men and women. Season of birth was not associated with sleep timing in Chinese adults.
authors.affiliation: Department of Preventive Medicine, School of Public Health, Wannan Medical College, Wuhu 241001, China. huangyewindow@163.com.|Laboratory for Environment and Health, School of Earth and Environment, Anhui University of Science and Technology, Huainan 231001, China. huangyewindow@163.com.
authors.forename: Yuee
authors.initials: Y
authors.lastname: Huang
authors.affiliation: School of Science and Engineering, Tulane University, New Orleans, LA 70112, USA. dlin5@tulane.edu.
authors.forename: Dongdong
authors.initials: D
authors.lastname: Lin
authors.affiliation: Department of Environmental Toxicology, The Institute of Environmental and Human Health, Texas Tech University, Texas Tech University Health Sciences Center, Lubbock, TX 79416, USA. lu.chuanwen@gmail.com.
authors.forename: Chuanwen
authors.initials: C
authors.lastname: Lu
authors.affiliation: School of Medicine, Tulane University, 1430 Tulane Ave, New Orleans, LA 70112, USA. gali1@tulane.edu.
authors.forename: Gholam
authors.initials: G
authors.lastname: Ali
authors.affiliation: Histecon Associates, Inc. Little Rock, AR 72205, USA. jemetzger@aristotle.net.
authors.forename: James
authors.initials: J
authors.lastname: Metzger
authors.affiliation: Saw Swee Hock School of Public Health, National University of Singapore, 117549, Singapore. nivedita_shankar@nuhs.edu.sg.
authors.forename: Nivedita
authors.initials: N
authors.lastname: Shankar
authors.affiliation: Department of Epidemiology, School of Public Health, Medical College of Soochow University, Suzhou 215123, China. xutan@suda.edu.cn.|Department of Epidemiology, School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA 70112, USA. xutan@suda.edu.cn.
authors.forename: Tan
authors.initials: T
authors.lastname: Xu
authors.affiliation: School of Food Science, Guangdong Pharmaceutical University, Zhongshan 528458, China. huangyewindow@163.com.|School of Public Health and Tropical Medicine, Tulane University, New Orleans, LA 70112, USA. huangyewindow@163.com.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Sun
authors.affiliation: Department of Epidemiology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Beijing 100005, China. guangliang_shan@hotmail.com.|School of Basic Medicine, Peking Union Medical College, Beijing 100005, China. guangliang_shan@hotmail.com.
authors.forename: Guangliang
authors.initials: G
authors.lastname: Shan
mesh_terms: D000328:Adult; D044466:Asian People; D002681:China; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D036801:Parturition; D012621:Seasons; D012890:Sleep; D011795:Surveys and Questionnaires; D013997:Time Factors
keywords: season of birth; sex; sleep timing