title: Mismatch of Sleep and Work Timing and Risk of Type 2 Diabetes.
abstract: OBJECTIVE
  To examine whether a mismatch between chronotype (i.e., preferred sleep timing) and work schedule is associated with type 2 diabetes risk.
  
  
  METHODS
  In the Nurses' Health Study 2, we followed 64,615 women from 2005 to 2011. Newly developed type 2 diabetes was the outcome measure (n = 1,452). A question on diurnal preference ascertained chronotype in 2009; rotating night shift work exposure was assessed regularly since 1989.
  
  
  RESULTS
  Compared with intermediate chronotypes, early chronotypes had a slightly decreased diabetes risk after multivariable adjustment (odds ratio 0.87 [95% CI 0.77-0.98]), whereas no significant association was observed for late chronotypes (1.04 [0.89-1.21]). Among early chronotypes, risk of type 2 diabetes was modestly reduced when working daytime schedules (0.81 [0.63-1.04]) and remained similarly reduced in women working <10 years of rotating night shifts (0.84 [0.72-0.98]). After ≥10 years of shift work exposure, early chronotypes had a nonsignificant elevated diabetes risk (1.15 [0.81-1.63], Ptrend = 0.014). By contrast, among late chronotypes, the significantly increased diabetes risk observed among day workers (1.51 [1.13-2.02]) appeared largely attenuated if their work schedules included night shifts (<10 years: 0.93 [0.76-1.13]; ≥10 years: 0.87 [0.56-1.34]; Ptrend = 0.14). The interaction between chronotype and shift work exposure was significant (Pinteraction = 0.0004). Analyses restricting to incident cases revealed similar patterns.
  
  
  CONCLUSIONS
  In early chronotypes, type 2 diabetes risk increased with increasing duration of shift work exposure, whereas late types had the highest diabetes risk working daytime schedules. These data add to the growing body of evidence that workers could benefit from shift schedules minimizing interference with chronotype-dependent sleep timing.
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA celine.vetter@channing.harvard.edu.
authors.forename: Céline
authors.initials: C
authors.lastname: Vetter
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA.
authors.forename: Elizabeth E
authors.initials: EE
authors.lastname: Devore
authors.affiliation: Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD.
authors.forename: Cody A
authors.initials: CA
authors.lastname: Ramin
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA Department of Environmental Health, Harvard T.H. Chan School of Public Health, Boston, MA.
authors.forename: Frank E
authors.initials: FE
authors.lastname: Speizer
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, MA.
authors.forename: Walter C
authors.initials: WC
authors.lastname: Willett
authors.affiliation: Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA.
authors.forename: Eva S
authors.initials: ES
authors.lastname: Schernhammer
mesh_terms: D000328:Adult; D002940:Circadian Rhythm; D003924:Diabetes Mellitus, Type 2 / Q000209:etiology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008875:Middle Aged; D009784:Occupational Diseases / Q000209:etiology*; D016272:Occupational Health; D016017:Odds Ratio; D012307:Risk Factors; D012893:Sleep Wake Disorders / Q000150:complications*; D014851:Wakefulness; D014940:Work Schedule Tolerance