title: Diurnal cortisol variation is associated with nocturnal blood pressure dipping.
abstract: OBJECTIVE
  To investigate if diurnal cortisol variation is associated with nocturnal blood pressure (BP) dipping.
  
  
  METHODS
  In this study, 302 healthy adults (51% female; average age 31 years) underwent 24-hour ambulatory BP assessment with BP measured randomly approximately every 20 minutes during waking hours and every hour during sleep. Salivary cortisol was obtained at five time points. Cortisol and BP have natural diurnal variations and disruptions in these diurnal variations are related to pathological conditions, such as greater risk for cardiovascular disease. A lack of a drop in cortisol from day to night and a lack of a drop in BP from waking to sleeping have both been associated with negative outcomes. It is not known, however, if diurnal variations in cortisol and BP are related, or if changes in cortisol from day to night influence BP dipping.
  
  
  RESULTS
  Diurnal cortisol variation was a significant predictor of BP dipping. Controlling for gender, body mass index, age, phase of menstrual cycle, sleep quality, morning cortisol, and daytime measures of the relevant cardiovascular assessments did not significantly affect the results. Cortisol variation was found to have a stronger relationship with BP dipping than any of the covariates measured.
  
  
  CONCLUSIONS
  Decreased diurnal variation in cortisol is associated with decreased diurnal variation in BP. Future studies could benefit from examining how these two variables interact in predicting disease outcomes.
authors.affiliation: Department of Psychology, Brigham Young University, Provo, Utah 84602-5543, USA. julianne_holt-lunstad@byu.edu
authors.forename: Julianne
authors.initials: J
authors.lastname: Holt-Lunstad
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Steffen
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm; D005260:Female; D006801:Humans; D006854:Hydrocortisone / Q000032:analysis*; D008297:Male; D012463:Saliva / Q000737:chemistry
chemical_list: D006854:Hydrocortisone