Blood pressure and cardiovascular parameters during sleep arousals

Sleep arousal is generally known as a transient episode of wakefulness into the sleepiness. Sleep arousals can be classified based on their association and accompany with pathological episodes. In this paper, our objective was to find out whether various types of sleep arousals influence on blood pressure and Heart Rate Variability (HRV). We analysed continuous Diastolic and Systolic Blood Pressures (DBP and SBP), Pulse Transit Time (PTT) as well as High and Low Frequency components (HF and LF) of HRV in different types of arousals. We developed Slope Index (SI) to determine whether a feature was ascending or descending before, during and after the occurrence of a sleep arousal. Slope Index Positive Percentage (SIPP) was created and computed for all features to find out the percentage of arousals with an ascending trend of a cardiovascular feature. In pre-arousal epochs, we obtained SIPP_DBP= 48.9%, SIPP_SBP = 48.2% and SIPP_LF = 41%. Whilst during the arousal episodes, the SIPP_DBP, SIPP_SBP and SIPP_LF increased to 57.2%, 57.4% and 78.9%, correspondingly. This means that during arousal occurrence these parameters were likelier to rise. Whereas SIPP of PTT and HF component of HRV during arousals were less than prearousal. This indicated PTT and HF were highly probable to drop during the arousal than to rise. The high SIPP_DBP and SIPP_SBP parameters, approximately 76%, during the arousals indicates that sleep arousals may cause a sudden increase in blood pressure.