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Sleep-related changes in baroreflex sensitivity and cardiovascular autonomic modulation
Jacopo M Legramante1, Maria G Marciani, Fabio Placidi
1Dipartimento di Medicina Interna-Centro di Riabilitazione Cardiologica San Raffaele-Pisana, Université di Roma, Rome, Italy. legramante@med.uniroma2.it
Journal of Hypertension
|July 23, 2003
Summary
Baroreflex sensitivity (BRS) during sleep varies with stimuli and sleep stage. It increases with hypertensive stimuli during REM sleep, especially later in the night, showing sleep cycle-dependent baroreflex control.
Area of Science:
- Cardiovascular physiology
- Sleep science
- Autonomic nervous system function
Background:
- Baroreflex sensitivity (BRS) is crucial for maintaining blood pressure homeostasis.
- Sleep stages, particularly REM sleep, are associated with autonomic nervous system fluctuations.
- Understanding baroreflex control during sleep is vital for cardiovascular health.
Purpose of the Study:
- To investigate the impact of different sleep stages on baroreflex sensitivity (BRS).
- To examine heart rate and blood pressure variability during sleep.
- To test if baroreflex control differs in response to hypertensive and hypotensive stimuli across sleep cycles.
Main Methods:
- Polygraphic sleep recordings in 10 healthy males.
- Continuous recording of blood pressure (BP) and RR intervals.
- Calculation of BRS using the sequences method and analysis of variability using autoregressive power spectral analysis.
Main Results:
- BRS significantly increased during REM sleep in response to hypertensive stimuli compared to NREM sleep and wakefulness.
- BRS did not change in response to hypotensive stimuli during REM sleep.
- BRS responses during REM sleep varied across different sleep cycles, being more pronounced later in the night.
Conclusions:
- Arterial baroreflex modulation of the sinus node differs between hypotensive and hypertensive stimuli, especially during REM sleep.
- Baroreflex control exhibits non-uniform behavior during REM sleep across different nocturnal sleep cycles.
- The arterial baroreflex is more effective in buffering sympathetic activation during REM sleep towards the end of sleep.