Assessment of the Cardiac Response to Sleep Arousal

Sleep arousal or transient unconscious wakefulness is a part of normal sleep. However, once its frequency increases, it may disturb the sleep and make it fragmented. The objective of this study is to assess the effect of sleep arousals on cardiovascular function. We investigated cardiac responses to sleep arousal in a large sample comprising 2656 older men. We quantified beat-to-beat QT and RR time intervals on ECG 15 s prior and following to arousal onset. Obtained results show that in more than three-quarters of the men, the average RR interval shortened during arousal compared to pre-and post-arousal intervals, while less than half of the men experienced average QT interval shortening during arousals. The QT and RR variability increased significantly during arousal, where RR variability changes were more prominent than QT variability changes. The QT variability index was weakly correlated with the apnea–hypopnea index and arousal index. In conclusion, arousal episodes trigger cardiovascular function, and their effect can be measured and quantified through cardiac QT and RR time intervals.