Sleep and Post-traumatic Stress Disorder

In “Multiple memories can be simultaneously reactivated during sleep as effectively as a single memory,” Eitan Schechtman et al. examine targeting specific memories by presenting learning-related stimuli (e.g. a sound) during slow-wave sleep to selectively enhance memory with sets of one, two, or six items. The results show that cued items, regardless of set size, improved memory of the target information; there was no significant effect of group size on memory consolidation. This paradigm, called targeted memory reactivation (TMR), has been shown to improve vocabulary learning, motor skill learning, and even reduce social biases. During his presentation at Loyola University Chicago in December of 2019, Dr. Schechtman shared that he uses this technique in his laboratory to enhance forgetting as well. In short, presenting a sound during sleep that was previously paired with a set of items that participants were instructed to forget resulted in a decreased ability to place these items onto their proper locations on a grid. The working theory behind this is that there was reactivation of both the items and the suppression instruction. The results he finds about memory suppression being enhanced during sleep raised an important question and future research direction for Dr. Schechtman: Could targeted memory reactivation be used to treat post-traumatic stress disorder (PTSD)? The relationship between sleep and memory has become a topic of great interest for many researchers. 

Researchers at the Department of Psychiatry and Behavioral Sciences at Howard University looked at the relationship between sleep and adaptive emotional processing after written narrative exposure (WNE) to memories of traumatic events in participants with clinical PTSD symptoms. Written narrative exposure works to restructure the trauma narratives in people with trauma-spectrum disorders. Patients create a chronological narrative of their lives, including their traumatic experience(s) as well as positive elements. This contextualization of their trauma helps patients redefine and comprehend the memory of their trauma (“Narrative Exposure Therapy (NET),” 2017). In this study, researchers found a significant reduction is PTSD symptom severity after written narrative exposure sessions, comparing N1, N2 and N3 changes, total sleep duration, and eye movement during REM sleep before and after the treatment. Lowered arousal during sleep suggests fewer intrusive trauma memories.

During Dr. Schechtman’s presentation, he mentioned the potential of suppressing memories in PTSD patients using TMR by pairing either a sound or odor with the traumatic memory and then working to suppress it during sleep. Both the idea presented here as well as the study done at Howard University get at transforming the mind’s approach to the memory of the traumatic event. While every person’s trauma is different, strategies like the ones mentioned above provide the framework of utilizing a generalized approach to diminish the effects of post-traumatic stress disorder. This is very important to consider as current therapies and medications do not work for everyone suffering from this disorder. 


References 
Kobayashi, I., Mellman, T. A., Altaee, D., Howell, M. K., & Lavela, J. (2016). Sleep and Processing of Trauma Memories. Journal of Traumatic Stress, 29(6), 568–571. https://doi-org.flagship.luc.edu/10.1002/jts.22137

“Narrative Exposure Therapy (NET).” American Psychological Association, American Psychological Association, 2017, www.apa.org/ptsd-guideline/treatments/narrative- exposure-therapy.

Schechtman, Eitan, et al. “Multiple Memories Can Be Simultaneously Reactivated during Sleep as Effectively as a Single Memory.” 2019, doi:10.1101/662015.