Comparing of inter-session change in parasympathetic tone following habituation in individuals who slept versus those who remained awake between sessions

Abstract

Archival data from a previous study (Pace-Schott et al., 2012) will be used to evaluate whether, following an intra-session habituation of autonomic responses, subsequent sleep vs. wakefulness results in different degrees of autonomic activation when the aversive stimulus is again encountered (inter-session habituation). Intra- and inter-session habituation was indexed by the degree of parasympathetic outflow quantified using heart-rate variability measures. Researchers have emphasized the importance of finding ways to improve the outcome of exposure therapy, if therapeutic benefits were improved, more patients could potentially achieve symptom remission (McGuire et al., 2014). Sleep has been found to supplement the therapeutic effectiveness of exposure therapy. The purpose of this study is to develop the research on sleep and habituation; the study investigates evidence of sleep dependent habituated memory consolidation in terms of heart rate variability. Since sleep consolidates memory, after sleeping one would retain more of the habituation, hence being calmer than if you remained awake. This study seeks to test the hypothesis that participants who sleep will show higher activation of their parasympathetic nervous system following exposure to arousing stimuli than those who remain awake. In other words, we predict that the two parasympathetic indices, RMSSD and LOG HF will increase following sleep than they would following wake. Heart rate variability (HRV) is a good index of sympathetic nervous system activation since this measure is provoked by the fight or flight response of the SNS. Heart rate variability can demonstrate the activation of the autonomic nervous system and indicate activation of either the sympathetic or parasympathetic nervous system. HRV is important for emotional experiences because it the ability one has of adjusting the activation of the parasympathetic nervous system is related to the ability to adjust emotions and physical experiences; this correlates with the hearts ability to adjust beat to beat intervals.