NREM Sleep EEG Characteristics Following Written Trauma Memory Exposure: An Exploratory Study of Power and Spindle-Phase Dynamics

Abstract

Trauma-focused psychotherapy aims to process intrusive memories in trauma survivors, and sleep is thought to contribute to offline memory consolidation and updating following therapy. We explored associations between posttraumatic stress disorder (PTSD) symptom severity, treatment outcomes and three sleep EEG metrics during posttherapy naps: frequency-band power, symmetry and spindle to slow oscillation phase-coupling. These metrics have previously been linked to PTSD symptom severity, emotion regulation in the waking state and memory consolidation, respectively. Data were collected from 17 inpatients with a subthreshold PTSD diagnosis who all suffered from recurring intrusive trauma memories. Patients underwent three sessions of written exposure therapy (WET), a form of trauma-focused therapy, followed by 90-min sleep recordings using a portable EEG device. PTSD symptom (PTSS) severity was evaluated using a clinician-administered interview (CAPS-5). Initial observations suggest a reduction in EEG power across the Theta, Alpha, Sigma and Gamma bands was observed during deep sleep across WET-nap sessions, with a low Delta/Alpha ratio potentially predicting symptom change in reexperiencing. Alpha band symmetry correlated with overall PTSS severity but not improvement throughout the course of treatment. Finally, a phase shift in spindle nesting towards the late slow oscillation upstates was found the right hemisphere from WET Sessions 1–3 and correlated with overall PTSS reduction. Although these preliminary findings from our naturalistic clinical sample cannot establish causal relationships due to the lack of appropriate controls, they provide initial insights that may guide future controlled investigations into the complex interplay between sleep physiology and trauma-focused interventions.