title: Daytime napping, sleep duration and increased 8-year risk of type 2 diabetes in a British population.
abstract: Few studies have prospectively examined the relationship between daytime napping and risk of type 2 diabetes. We aimed to study the effects of daytime napping and the joint effects of napping and sleep duration in predicting type 2 diabetes risk in a middle- to older-aged British population.
  
  
  
  In 1998-2000, 13 465 individuals with no known diabetes participating in the European Prospective Investigation into Cancer-Norfolk study reported daytime napping habit and 24-h sleep duration. Incident type 2 diabetes cases were identified through multiple data sources until 31 July 2006. After adjustment for age and sex, daytime napping was associated with a 58% higher diabetes risk. Further adjustment for education, marital status, smoking, alcohol intake, physical activity, comorbidities and hypnotic drug use had little influence on the association, but additional adjustment for BMI and Waist Circumference attenuated the Odds ratio (OR) (95% CI) to 1.30 (1.01, 1.69). The adjusted ORs (95% CI) associated with short and long sleep duration were 1.46 (1.10, 1.90) and 1.64 (1.16, 2.32), respectively. When sleep duration and daytime napping were examined together, the risk of developing diabetes more than doubled for those who took day naps and had less than 6 h of sleep, compared to those who did not nap and had 6-8 h of sleep.
  
  
  
  Daytime napping was associated with an increased risk of type 2 diabetes, particularly when combined with short sleep duration. Further physiological studies are needed to confirm the interaction between different domains of sleep in relation to diabetes risk.
authors.affiliation: Institute of Public Health, University of Cambridge, UK. Electronic address: yue.leng@ucsf.edu.
authors.forename: Y
authors.initials: Y
authors.lastname: Leng
authors.affiliation: Division of Mental Health & Wellbeing, Warwick Medical School, University of Warwick, Coventry, UK.
authors.forename: F P
authors.initials: FP
authors.lastname: Cappuccio
authors.affiliation: Institute of Public Health, University of Cambridge, UK.
authors.forename: P G
authors.initials: PG
authors.lastname: Surtees
authors.affiliation: Institute of Public Health, University of Cambridge, UK.
authors.forename: R
authors.initials: R
authors.lastname: Luben
authors.affiliation: Institute of Public Health, University of Cambridge, UK.
authors.forename: C
authors.initials: C
authors.lastname: Brayne
authors.affiliation: Institute of Public Health, University of Cambridge, UK.
authors.forename: K-T
authors.initials: KT
authors.lastname: Khaw
mesh_terms: D050154:Adiposity; D000367:Age Factors; D000368:Aged; D015992:Body Mass Index; D016009:Chi-Square Distribution; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis / Q000453:epidemiology* / Q000503:physiopathology; D005260:Female; D006184:Habits; D006801:Humans; D015994:Incidence; D008019:Life Style; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D012890:Sleep; D013997:Time Factors; D006113:United Kingdom / Q000453:epidemiology; D055105:Waist Circumference
keywords: Cohort; Epidemiology; Prospective; Sleep; Type 2 diabetes