title: Is the chronotype associated with obstructive sleep apnea?
abstract: OBJECTIVE
  Chronotype and obstructive sleep apnea (OSA) appear to have a similar lifelong evolution, which could indicate a possible effect of morningness or eveningness in the apnea-hypopnea index (AHI). The present study aimed to examine the prevalence of chronotypes in a representative sample of São Paulo city residents and to investigate the effect of chronotypes on the severity of OSA.
  
  
  METHODS
  We performed a cross-sectional analysis using the São Paulo Epidemiologic Sleep Study (EPISONO). All participants underwent a full-night polysomnography and completed the Morningness-eveningness, Epworth Sleepiness Scale, and UNIFESP Sleep questionnaires. Chronotypes were classified as morning-type, evening-type, and intermediate.
  
  
  RESULTS
  Morning-type individuals represented 52.1% of the sample, followed by intermediate (39.5%), and evening-type (8.4%) individuals. After stratifying the sample by body mass index (BMI) (>26.8 kg/m(2)) and age (>42 years), we observed increased AHI values in morning- and evening-type individuals.
  
  
  CONCLUSIONS
  We demonstrated, for the first time, an age- and BMI-related effect of morning- and evening-types in OSA severity, suggesting that the intermediate chronotype might play a role as a protective factor in older and overweight patients.
authors.affiliation: Departamento de Psicobiologia, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Lenise Jihe
authors.initials: LJ
authors.lastname: Kim
authors.forename: Fernando Morgadinho
authors.initials: FM
authors.lastname: Coelho
authors.forename: Camila
authors.initials: C
authors.lastname: Hirotsu
authors.forename: Lia
authors.initials: L
authors.lastname: Bittencourt
authors.forename: Sergio
authors.initials: S
authors.lastname: Tufik
authors.forename: Monica Levy
authors.initials: ML
authors.lastname: Andersen
mesh_terms: D000328:Adult; D000367:Age Factors; D015992:Body Mass Index; D001938:Brazil; D002940:Circadian Rhythm; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017286:Polysomnography; D012307:Risk Factors; D020181:Sleep Apnea, Obstructive / Q000175:diagnosis* / Q000453:epidemiology*; D013223:Statistics as Topic