Investigating the effect of a nap following experimental trauma on analogue PTSD symptoms

Abstract

Cognitive models assume that the incomplete integration of a traumatic experience into the autobiographical memory results in typical symptoms associated with post-traumatic stress disorder (PTSD) such as intrusive re-experiencing. Sleep supports the integration of new experiences into existing memory networks through memory consolidation. In fifty-six females, we investigated whether a 90-min daytime nap (n = 33) compared to a wake period (n = 23) after being exposed to an experimental trauma (i.e. a trauma film) prevents PTSD analogue symptoms. Intrusive memories were recorded for seven days using a diary, overall PTSD symptoms were assessed using the Impact of Event Scale (IES-R) and affective response to trauma cues were measured one week after experimental trauma. The two groups did not differ in any of the analogue PTSD symptoms. However, participants obtaining rapid eye movement (REM) sleep in the nap experienced less distressing intrusive memories. Moreover, the duration of REM sleep and slow wave activity was negatively correlated with analogue PTSD symptoms. Our findings suggest that even a short sleep period after experimental trauma can play a protective role in trauma memory formation but only if the nap contains REM sleep. Our data provide additional evidence for a critical role of REM sleep in PTSD development.

Does Sleep Selectively Strengthen Certain Memories Over Others Based on Emotion and Perceived Future Relevance?

“…Looking at literature published from 2018 and forward only, this is often cited as a fact or as the typical finding. 7,9,16,18,19,21,[24][25][26][27][28][29][30]…”

Go to Bed and You MIGHT Feel Better in the Morning—the Effect of Sleep on Affective Tone and Intrusiveness of Emotional Memories

“…One study [17] found higher responses in the sleep group at a retest immediately after the delay interval, but lower responses at a second re-test taking place one week later. One study found no group differences [16], and another study found no effect of pharmacological norepinephrine reduction during sleep on subsequent heart rate responses to emotional stimuli [33]. One study combining participants suffering from PTSD with both trauma-exposed and non-trauma-exposed controls found sleep to decrease responses in several different heart rate-related measures [42].…”

“…This latter effect was however not replicated in a design comparing daytime wake with nighttime sleep [59]. One study found no differences in intrusions or in intrusion distress (after removing two outliers) between a sleep and a sleep deprivation group [60], and one study found no differences in the number of intrusions, intrusion distress, or on scores on the Impact of Event Scale between a nap and wake group [16]. Some studies on this topic have been correlational and observational rather than experimental.…”

“…In this study, compared to a control group that watched a neutral film, the trauma film watchers had increased wake after sleep onset, shorter stage 2 sleep, and longer slow-wave sleep duration, once again indicating that a certain sleep pattern can be a marker of a negative event rather than a causal mechanism for future symtoms. Wilhelm et al [16] found that increased affective responses to the trauma film was associated with it taking taking a longer time to fall asleep, and in decreased REM duration.…”

“…The opposite was, however, found in the group of participants who had received instructions to remember, with lower responses after sleep deprivation. The two studies that have examined if sleep makes emotional memories previously subjected to suppression (during encoding or retrieval respectively) either more or less accessible for voluntary retrieval have not found any such effects [70,71].…”