Sleep and Processing of Trauma Memories.

Sleep has been implicated in learning processes that appear to underlie recovery from posttraumatic stress disorder (PTSD). The importance of quality and timing of sleep following exposure-based therapies has been suggested. The present study evaluated relationships between sleep and adaptive emotional processing following written narrative exposure (WNE) to memories of traumatic events experienced by participants with clinically significant PTSD symptoms. Participants included 21 urban-residing nontreatment-seeking adults with full or subthreshold symptoms of PTSD who completed 4 sessions of 30-min WNE with the first session either in the evening or the morning. There was a significant reduction of PTSD symptom severity after WNE sessions (partial η = .65), but there was no interaction between group assignment based on the initial session's proximity to sleep and initial reduction of PTSD symptom severity (partial η = .01). Polysomnography following evening WNE revealed increased duration of total sleep and N2%, reduced N3%, and increased eye movement density during REM sleep compared with baseline recordings (dz = 0.65 to 1.15). Reduced N3% and increased REM density were associated with less improvement of PTSD symptoms (r = .58 & -.63). These findings suggest a relationship between preservation of diminished arousal during sleep and adaptive trauma memory processing.