title: Sympathetic overactivity due to sleep fragmentation is associated with elevated diurnal systolic blood pressure in healthy elderly subjects: the PROOF-SYNAPSE study.
abstract: OBJECTIVE
  Sleep fragmentation is a landmark of sleep disorders, because microarousals are systematically associated with sympathetic surges (i.e., sympathetic arousals). However, the impact of sympathetic sleep fragmentation on blood pressure (BP) remains understudied. We assessed the relationships between 24 h ambulatory BP monitoring, the autonomic arousal index (AAI) derived from pulse transit time, and heart rate variability indices. We hypothesized that repeated sympathetic arousals during sleep are associated with elevated BP in a large population of elderly volunteers.
  
  
  RESULTS
  Volunteer subjects (n = 780, 57.4% women) with a mean age of 68.7 years and free of known sleep-disordered breathing, coronary heart diseases, and neurological disorders underwent polygraphy, 24 h ECG Holter monitoring, and 24 h ambulatory BP monitoring. Multivariate regressions showed that sleep fragmentation, expressed by AAI, was associated with elevated diurnal (P = 0.008) and 24 h (P = 0.005) systolic BP and higher risk for 24 h [odds ratio (OR): 1.70 (1.04-2.80), P = 0.036] systolic hypertension, independently of confounders such as sleep-disordered breathing, body mass index, sex, diabetes, hypercholesterolaemia, and self-reported sleep duration and quality. Increased AAI was associated with higher nocturnal and diurnal low-frequency power (P < 0.001) and low-to-high-frequency ratio (P < 0.001), suggesting nocturnal and diurnal sympathetic overactivity.
  
  
  CONCLUSIONS
  In healthy elderly subjects, repetitive sympathetic arousals during sleep are associated with elevated systolic BP and higher risk of hypertension, after controlling for confounders. Sympathetic overactivity is the proposed underlying mechanism.
  
  
  BACKGROUND
  NCT00766584 and NCT00759304.
authors.affiliation: EA 4607 SNA-EPIS, Service de Physiologie Clinique et de l'Exercice, Pole NOL, CHU Nord, Faculté de Médecine Jacques Lisfranc, Université Jean Monnet, Saint-Etienne, PRES Université de Lyon, France. florianchouchou@gmail.com
authors.forename: F
authors.initials: F
authors.lastname: Chouchou
authors.forename: V
authors.initials: V
authors.lastname: Pichot
authors.forename: J L
authors.initials: JL
authors.lastname: Pépin
authors.forename: R
authors.initials: R
authors.lastname: Tamisier
authors.forename: S
authors.initials: S
authors.lastname: Celle
authors.forename: D
authors.initials: D
authors.lastname: Maudoux
authors.forename: A
authors.initials: A
authors.lastname: Garcin
authors.forename: P
authors.initials: P
authors.lastname: Lévy
authors.forename: J C
authors.initials: JC
authors.lastname: Barthélémy
authors.forename: F
authors.initials: F
authors.lastname: Roche
mesh_terms: D000368:Aged; D001143:Arousal / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D018660:Blood Pressure Monitoring, Ambulatory; D002940:Circadian Rhythm / Q000502:physiology*; D015716:Electrocardiography, Ambulatory; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D010808:Physical Examination; D017286:Polysomnography; D011446:Prospective Studies; D012892:Sleep Deprivation / Q000503:physiopathology*; D013564:Sympathetic Nervous System / Q000502:physiology*
keywords: Elderly; Heart rate variability; Hypertension; Pulse transit time; Sleep; Sympathetic activity