Daytime sympathetic hyperactivity in OSAS is related to excessive daytime sleepiness

Vincenzo Donadio, Rocco Liguori, Roberto Vetrugno, Manuela Contin, Mikael Elam, B. Gunnar Wallin, Tomas Karlsson, Enrico Bugiardini, Agostino Baruzzi, Pasquale Montagna

Research output: Contribution to journalArticlepeer-review


The aim of this study was to investigate the relationships among sympathetic hyperactivity, excessive daytime sleepiness (EDS) and hypertension in obstructive sleep apnoea syndrome (OSAS). Ten newly diagnosed OSAS patients with untreated EDS and daytime hypertension underwent polysomnography (PSG) and daytime measurements of plasma noradrenaline (NA), ambulatory blood pressure (BP), muscle sympathetic nerve activity (MSNA) by microneurography and objective assessment of EDS before and during 6 months of compliance-monitored continuous positive airway pressure (CPAP) treatment. One month after the start of CPAP, BP, MSNA and NA were significantly lowered, remaining lower than baseline also after 3 and 6 months of treatment. CPAP use caused a significant improvement of sleep structures, and reduced EDS. A statistical correlation analysis demonstrated that EDS was not correlated with sleep measures obtained from baseline PSG (% sleep stages, apnoea and arousal index, mean oxygen saturation value), whereas daytime sleepiness was significantly correlated with MSNA. Furthermore, MSNA and BP showed no correlation. Our data obtained from selected patients suggest that the mechanisms inducing EDS in OSAS are related to the degree of daytime sympathetic hyperactivity. Additionally, resting MSNA was unrelated to BP suggesting that factors other than adrenergic neural tone make a major contribution to OSAS-related hypertension. The results obtained in this pilot study need, however, to be confirmed in a larger study involving more patients.

Original languageEnglish
Pages (from-to)327-332
Number of pages6
JournalJournal of Sleep Research
Issue number3
Publication statusPublished - Aug 2007


  • Continuous positive airway pressure
  • Hypertension
  • Muscle sympathetic nerve activity
  • Obstructive sleep apnoea syndrome
  • Sleepiness

ASJC Scopus subject areas

  • Neuroscience(all)
  • Physiology


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