title: [Sleep-wakefulness variations in arterial stiffness: assessment using ambulatory recording of arterial pulse transit time].
abstract: OBJECTIVE
  The incidence of cardiovascular events is related to the sleep-wakefulness cycle. In particular, the magnitude and speed of the changes in hemodynamic variables that occur during transitions between wakefulness and sleep and between sleep and wakefulness are regarded as factors that either predict or determine target organ damage and cardiovascular risk. Although increased arterial stiffness (AS) is associated with the development of cardiovascular abnormalities, it is not known whether there exist any changes in AS that are associated with circadian variations in the incidence of cardiovascular events. The aims of this study were to assess AS in healthy subjects over a 24-hour period, to characterize any differences that occur between sleep and wakefulness, and to investigate any changes in AS that occur during the transition from wakefulness to sleep or from sleep to wakefulness.
  
  
  METHODS
  Twenty healthy volunteers with a dipper circadian blood pressure pattern underwent 24-hour ambulatory monitoring of blood pressure, heart rate and AS. In practice, AS was determined using the aorta-brachial pulse transit time and fractional pulsatility indices. Myocardial oxygen consumption was quantified using the double product (DP). An average was calculated for all variables for periods of sleep (23:00 to 06:00) and wakefulness (8:00 to 21:00) and for transitions from wakefulness to sleep (20:00 vs. 02:00) and from sleep to wakefulness (06:00 vs. 10:00 hours).
  
  
  RESULTS
  In complete contrast to DP, AS was greater during sleep than wakefulness (P< .05). Moreover, the changes in AS that occurred during transitions from wakefulness to sleep and from sleep to wakefulness were the opposite of those observed in DP (P< .05).
  
  
  CONCLUSIONS
  Arterial stiffness was greater during sleep than wakefulness, increased during the transition from wakefulness to sleep, and decreased during the transition from sleep to wakefulness.
authors.affiliation: Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
authors.forename: Sebastián
authors.initials: S
authors.lastname: Lluberas
authors.forename: Daniel
authors.initials: D
authors.lastname: Bia
authors.forename: Yanina
authors.initials: Y
authors.lastname: Zócalo
authors.forename: Mabel
authors.initials: M
authors.lastname: Zabalza
authors.forename: Carolina
authors.initials: C
authors.lastname: Etchart
authors.forename: Ricardo
authors.initials: R
authors.lastname: Armentano
mesh_terms: D000328:Adult; D001158:Arteries / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm / Q000502:physiology*; D004548:Elasticity; D005260:Female; D006801:Humans; D008297:Male; D011674:Pulse; D012890:Sleep / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*