Sleep Preserves Physiological Arousal in Emotional Memory

Abstract

Traumatic experiences are associated with increased emotional arousal. Overnight consolidation strengthens the episodic content of emotional memories, but it is still unclear how sleep influences the associated arousal response. To investigate this question, we compared the effects of sleep and wake on psychophysiological and subjective reactivity during emotional memory retrieval. Participants provided affective ratings for negative and neutral images while heart rate deceleration (HRD) and skin conductance responses (SCRs) were monitored. Following a 12-hour delay of sleep or wakefulness, participants completed an image recognition task where HRD, SCRs and affective ratings were recorded again. HRD responses to previously-encoded (“old”) negative images were preserved after sleep but diminished after wakefulness. No between-group difference in HRD was observed for novel negative images at recognition, indicating that the effects of sleep for old images were not driven by a generalised overnight increase in visceral activity, or circadian factors. No significant effects of sleep were observed for SCRs or subjective ratings. Our data suggest that cardiac arousal experienced at the time of encoding is sensitive to plasticity-promoting processes during sleep in a similar manner to episodic aspects of emotional memory.

The Comparison of Emotional Dysregulation and Experiential Avoidance in Patients with Insomnia and Non-Clinical Population

“…17,29 These efforts are deliberate and conscious, which require the involvement of cognitive and intellectual functions, thereby increasing the mental and emotional arousal levels, decreasing the sleep quality. 30,31 The present study was a cross-sectional one. Therefore, it is important to examine the effects of independent variables on sleep disorders in longitudinal studies.…”

Future-relevant memories are not selectively strengthened during sleep

“…These findings also complement a broader literature, where selective sleep-associated memory effects are not always replicated. For example, emotionally salient information is widely considered to be particularly sensitive to consolidation during sleep [47], but many studies have failed to find a preferential impact of sleep on emotionally negative relative to neutral memories [6,[26][27][28][29]48]. To what extent, and under what conditions, sleep offers selective benefits to memory is therefore still largely unknown.…”

“…However, other findings concerning the selective influences of sleep have been somewhat contradictory. A number of studies have failed to observe a preferential benefit of sleep on emotionally negative relative to neutral memories [6,[25][26][27][28][29][30], and others have observed no impact of monetary reward on sleep-associated consolidation [31][32][33]. In recent work, knowledge of a future test had no impact on the overnight retention of declarative or nondeclarative memories [34], and failed to influence the neural correlates of memory retention after sleep [35].…”

Sleep differentially impacts involuntary intrusions and voluntary recognitions of lab‐analogue traumatic memories

“…Indeed, mounting evidences suggest sleep preferentially consolidates emotional memories and makes them long‐lasting (Cox et al., 2018; Hu et al., 2006; Wagner et al., 2001). Besides memories, a few studies suggested sleep may also preserve affective tones of emotional memories, indicated by subjective and physiological responses (Ashton et al., 2019; Baran et al., 2012; Menz et al., 2013; but also see Cox et al., 2018; Cunningham et al., 2014; Van Der Helm et al., 2011 for discrepant findings). Accordingly, one tenable hypothesis is that sleep deprivation in the early aftermath of trauma may alleviate PTSD symptoms, including involuntary intrusions and emotional hyperarousal.…”

“…memories, indicated by subjective and physiological responses (Ashton et al, 2019;Baran et al, 2012;Menz et al, 2013; but also see Cox et al, 2018;Cunningham et al, 2014;Van Der Helm et al, 2011 for discrepant findings). Accordingly, one tenable hypothesis is that sleep deprivation in the early aftermath of trauma may alleviate PTSD symptoms, including involuntary intrusions and emotional hyperarousal.…”