• polysomnography;
  • post-traumatic stress disorder;
  • sleep structure;
  • slow wave sleep deficit;
  • startle response

Aims:  The purpose of the present study was to investigate sleep structure in post-traumatic stress disorder (PTSD) patients with and without any psychiatric comorbidities. The relationship between sleep variables and measurements of clinical symptom severity were also investigated.

Methods:  Sleep patterns of 24 non-medicated male PTSD patients and 16 age- and sex-matched normal controls were investigated on polysomnography on two consecutive nights. Six PTSD-only patients and 15 PTSD patients with major depressive disorder (MDD) were also compared to normal controls. Sleep variables were correlated with PTSD symptoms.

Results:  Compared to the normal controls, the PTSD patients with MDD had difficulty initiating sleep, poor sleep efficiency, decreased total sleep time, decreased slow wave sleep (SWS), and a reduced rapid eye movement (REM) sleep latency. The PTSD patients without any comorbid psychiatric disorders had moderately significant disturbances of sleep continuity, and decreased SWS, but no abnormalities of REM sleep. REM sleep latency was inversely proportional to the severity of startle response. SWS was found to be inversely correlated with the severity of psychogenic amnesia.

Conclusions:  PTSD patients have disturbance of sleep continuity, and SWS deficit, without the impact of comorbid depression on sleep. The relationship between SWS and the inability to recall an important aspect of trauma may indicate the role of sleep in the consolidation of traumatic memories. The relationship between the severity of the startle response and REM latency may suggest that REM sleep physiology shares common substrates with the symptoms of PTSD.