title: Long-term changes in sleep duration, energy balance and risk of type 2 diabetes.
abstract: OBJECTIVE
  Baseline sleep duration has a U-shaped relationship with type 2 diabetes, but little research examines the associated changes. We examined long-term changes in sleep duration and concomitant changes in diet, physical activity, weight and subsequent diabetes.
  
  
  METHODS
  The cohort includes 59,031 women aged 55-83 years in the Nurses' Health Study without diabetes in 2000. Change in sleep duration is the difference between self-reported 24 h sleep duration in 1986 and 2000. Diet, physical activity and covariates were updated every 2-4 years. Self-reported diabetes was confirmed via validated questionnaires. Cox regression models were adjusted for 1986 sleep duration and 1986 values of diabetes risk factors, including BMI, and subsequently for change in covariates from 1986 to 2000.
  
  
  RESULTS
  We documented 3,513 incident diabetes cases through to 2012. Compared with no change, decreases in sleep duration were adversely associated with changes in diet quality and physical activity, while increases were associated with greater weight gain. After adjustment for 1986 covariates, HRs (95% CI) for ≤ -2, > -2 to < 0, > 0 to < 2 and ≥ 2 h/day changes in sleep duration (vs no change) were 1.09 (0.93, 1.28), 1.10 (1.001, 1.12), 1.09 (1.00, 1.18) and 1.30 (1.14, 1.46), respectively. Additional adjustment for diet and physical activity did not appreciably alter the results. Increases in sleep duration ≥ 2 h/day remained adversely associated with diabetes (HR [95% CI]: 1.15 [1.01, 1.30]) after adjustment for change in covariates, including BMI.
  
  
  CONCLUSIONS
  Increases in sleep duration among middle-aged and older women were modestly associated with risk of diabetes; changes in diet, physical activity and BMI did not explain associations.
authors.affiliation: Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA. emc611@mail.harvard.edu.|Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA. emc611@mail.harvard.edu.|Division of Research, Kaiser Permanente Northern California, 2000 Broadway, 5th Floor, Oakland, CA, 94612, USA. emc611@mail.harvard.edu.
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Cespedes
authors.affiliation: Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Shilpa N
authors.initials: SN
authors.lastname: Bhupathiraju
authors.affiliation: Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Li
authors.affiliation: Channing Division of Network Medicine, Harvard Medical School, Boston, MA, USA.|Department of Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Bernard
authors.initials: B
authors.lastname: Rosner
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.|Division of Sleep and Circadian Disorders, Departments of Medicine and Neurology, Brigham and Women's Hospital, Boston, MA, USA.
authors.forename: Susan
authors.initials: S
authors.lastname: Redline
authors.affiliation: Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA, USA.|Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Frank B
authors.initials: FB
authors.lastname: Hu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D001835:Body Weight; D015331:Cohort Studies; D003924:Diabetes Mellitus, Type 2 / Q000150:complications / Q000175:diagnosis* / Q000503:physiopathology*; D004032:Diet; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D008875:Middle Aged; D009043:Motor Activity; D016016:Proportional Hazards Models; D012307:Risk Factors; D057566:Self Report; D012890:Sleep; D012893:Sleep Wake Disorders / Q000150:complications; D011795:Surveys and Questionnaires
keywords: Body weight; Diabetes mellitus; Diet; Sleep