title: Sleep-related changes in hemodynamic and autonomic regulation in human hypertension.
abstract: OBJECTIVE
  The present study investigates the hemodynamic and autonomic regulation during sleep-awake transitions and across different sleep cycles in patients with essential hypertension.
  
  
  METHODS
  Nineteen individuals free of sleep apnea (10 normotensive and nine hypertensive matched for age, sex, and body mass index) underwent a standard polysomnography, with simultaneous electrocardiography and beat-to-beat blood pressure monitoring (Portapres). All measurements were determined while awake (before and after sleep), as well as in the beginning and at end of the sleep cycle (first/last cycle of nonrapid and rapid eye movement stages).
  
  
  RESULTS
  Systolic blood pressure was higher in hypertensives and exhibited a similar reduction to the normotensives ones in initial nonrapid eye movement sleep. This reduction was because of different mechanisms: a significant fall in cardiac output in normotensives, whereas in hypertensives was also dependent of a decrease in peripheral vascular resistance. Hypertensive patients presented lower heart rate variation and attenuated baroreflex sensitivity during sleep but not immediately before and after sleep. Spectral analysis suggested a higher sympathetic activity in the sleep stages in hypertension. Additionally, a progressive sympathetic predominance (final rapid eye movement > initial rapid eye movement and awake period postsleep > awake period presleep) was observed in both groups.
  
  
  CONCLUSIONS
  Hypertension is associated with depressed baroreflex sensitivity and increased sympathetic activation during sleep. The greater sympathetic predominance at the end of night (preceding the morning surge of sympathetic activity) could be implicated in the occurrence of cardiovascular events.
authors.affiliation: Hypertension Unit - Heart Institute (InCor), University of São Paulo Medical School, Av Dr Enéas Carvalho de Aguiar, 44, Zip Code 05403-904, São Paulo, Brazil. luciano.drager@incor.usp.br
authors.forename: Luciano F
authors.initials: LF
authors.lastname: Drager
authors.forename: Linda M
authors.initials: LM
authors.lastname: Ueno
authors.forename: Patrícia S
authors.initials: PS
authors.lastname: Lessa
authors.forename: Carlos E
authors.initials: CE
authors.lastname: Negrão
authors.forename: Geraldo
authors.initials: G
authors.lastname: Lorenzi-Filho
authors.forename: Eduardo M
authors.initials: EM
authors.lastname: Krieger
mesh_terms: D000328:Adult; D017704:Baroreflex / Q000502:physiology; D005260:Female; D006439:Hemodynamics; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D012890:Sleep / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology; D013564:Sympathetic Nervous System / Q000503:physiopathology*