The effects of repetitive arousal from sleep on cardiovascular autonomic control

A previous study found that the sympathoexcitatory cardiovascular effects of arousal are relatively long lasting. In this study, we examine (1) whether the cumulative effects of arousal can lead to significant changes in autonomic control and (2) how the frequency of arousals affect the magnitude of these effects. Ten healthy subjects were aroused from sleep every 30 seconds, 1 minute and 2 minutes of sleep for an hour. EEG, ABP, ECG and respiration were recorded, and the impulse responses of respiratory sinus arrhythmia (h/sub RSA/) and arterial baroreflex (h/sub ABR/) before and after 50 minutes of repetitive arousal were quantified by using a minimal closed loop cardiovascular model. We found that the low frequency baroreflex gain decreased after exposure to repetitive arousals of 2 minutes periodicity but remained unchanged in the control and other arousal conditions.