title: Is it time for bed? Short sleep duration increases risk of obesity in Mexican American children.
abstract: OBJECTIVE
  Cross-sectional studies show that sleep is related to childhood obesity. We aimed to examine the longitudinal impact of sleep on the risk of obesity in Mexican American children.
  
  
  METHODS
  We evaluated 229 Mexican American 8-10-year-olds and their mothers at baseline and at 12- and 24-month follow-ups. Sleep duration and anthropometrics were collected. Age- and gender-specific body mass index (BMI) z-scores (BMIz) were calculated based on Centers for Disease Control and Prevention guidelines. Sleep duration was estimated using accelerometry. Children were also categorized as long or short sleepers, using the National Sleep Foundation's recommendation to define adequate sleep duration (10-11 h for 5-12-year-olds). Using linear regressions, we examined whether sleep duration predicted BMIz, waist-to-height ratio (WHtR), and weight gain at 24 months.
  
  
  RESULTS
  Children were mostly short sleepers (82%). Children who slept less were more likely to have a higher BMIz, WHtR, and weight gain at the 24-month follow-up (β = -0.07, P = 0.01; β = -0.11, P <0.01; and β = -0.14, P = 0.02, respectively), after controlling for baseline weight status, child gender, maternal BMI, and occupation.
  
  
  CONCLUSIONS
  In Mexican American children, shorter sleep duration at baseline was associated with increased weight status over 24 months.
authors.affiliation: Division of General Pediatrics, University of CA, San Francisco, CA, USA. Electronic address: suzanna.martinez@ucsf.edu.
authors.forename: Suzanna M
authors.initials: SM
authors.lastname: Martinez
authors.affiliation: Department of Psychiatry, University of CA, San Francisco, CA, USA.
authors.forename: Jeanne M
authors.initials: JM
authors.lastname: Tschann
authors.affiliation: Kaiser Permanente, San Francisco, CA, USA.
authors.forename: Louise C
authors.initials: LC
authors.lastname: Greenspan
authors.affiliation: School of Public Health, University of CA, Berkeley, CA, USA.
authors.forename: Julianna
authors.initials: J
authors.lastname: Deardorff
authors.affiliation: School of Public Health, University of CA, Berkeley, CA, USA.
authors.forename: Carlos
authors.initials: C
authors.lastname: Penilla
authors.affiliation: Department of Counseling Psychology, University of San Francisco, San Francisco, CA, USA.
authors.forename: Elena
authors.initials: E
authors.lastname: Flores
authors.affiliation: Department of Psychiatry, University of CA, San Francisco, CA, USA.
authors.forename: Lauri A
authors.initials: LA
authors.lastname: Pasch
authors.affiliation: School of Medicine, University of CA, San Francisco, CA, USA.
authors.forename: Steve E
authors.initials: SE
authors.lastname: Gregorich
authors.affiliation: USDA/ARS Children Nutrition Research Center, Department of Pediatrics, Baylor College of Medicine, Houston, TX, USA.
authors.forename: Nancy F
authors.initials: NF
authors.lastname: Butte
mesh_terms: D061725:Accelerometry; D002140:California / Q000453:epidemiology; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D017058:Mexican Americans / Q000706:statistics & numerical data*; D063766:Pediatric Obesity / Q000209:etiology*; D012307:Risk Factors; D012892:Sleep Deprivation / Q000150:complications*
keywords: Accelerometer; Longitudinal; Mexican American children; Obesity; Sleep; Waist-to-height ratio