title: Infradian awake and asleep systolic and diastolic blood pressure rhythms in humans.
abstract: BACKGROUND
  Blood pressure shows 24-h rhythms with a significant seasonal fluctuation.
  
  
  OBJECTIVE
  To characterize 2-month to 12-month infradian rhythms in the mean awake and asleep systolic blood pressure (SBP) and diastolic blood pressure (DBP) in humans.
  
  
  METHODS
  A total of 1689 participants underwent 24-h ambulatory blood pressure monitoring during different periods of the year. The mean daily temperature, humidity, barometric pressure and wind velocity values for the same time span and geographical location were obtained. Fourier analysis was used to fit 12-month, 6-month, 4-month, 3-month and 2-month rhythms to the mean awake and asleep SBP and DBP and to metereological variables.
  
  
  RESULTS
  The awake mean SBP and DBP values showed significant 12-month and 3-month rhythms (respectively, R2 = 55%, P < 0.001 and R2 = 45% P < 0.001), with a peak in July (winter) and a trough-peak difference of 6.2 +/- 1.6 mmHg (P < 0.001, SBP) and 4.2 +/- 1.5 mmHg (P < 0.001, DBP). In contrast, asleep blood pressure means showed mainly 3-month rhythms (SBP, R2 = 19%, P < 0.02; DBP, R2 = 43% P < 0.02). Mean daily temperature and humidity showed at 12-month, 6-month, 4-month, 3-month and 2-month rhythms, barometric pressure showed 12-month and 6-month rhythms, and wind velocity showed 12-month and 3-month rhythms. Minimal temperature values and maximal humidity values coincided with elevated blood pressure values.
  
  
  CONCLUSIONS
  Awake blood pressure means exhibited mainly circannual fluctuations while asleep blood pressure means showed principally 3-month rhythms. Infradian blood pressure variations correlated with some meteorological variables.
authors.affiliation: Instituto de Investigaciones Cardiologicas, Prof. Dr. Alberto C. Taquini, Facultad de Medicina, Universidad de Buenos Aires, Argentina.
authors.forename: Santiago
authors.initials: S
authors.lastname: Perez-Lloret
authors.forename: Jorge E
authors.initials: JE
authors.lastname: Toblli
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Vigo
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Cardinali
authors.forename: José
authors.initials: J
authors.lastname: Milei
mesh_terms: D000368:Aged; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory / Q000379:methods*; D002940:Circadian Rhythm / Q000502:physiology*; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D008297:Male; D008685:Meteorological Concepts; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology; D015999:Multivariate Analysis; D012044:Regression Analysis; D012621:Seasons