Sleep microstructure deficits in posttraumatic stress disorder (PTSD) may ultimately represent a potential biomarker, according to a study published in Sleep. Sleep abnormalities, the most common symptom of PTSD, are observed in approximately 70% of patients, indicating that sleep problems may play an important role in the development and maintenance of the disorder.
Marieke de Boer, of the Department of Psychology, University of Amsterdam, The Netherlands, and colleagues assessed electroencephalogram power across a broad range of frequencies and scalp locations during both rapid eye movement (REM) and non-REM (NREM) sleep in individuals with past trauma exposure with (n=16; mean age, 45.6±7.9 years; 94% men) and without (n=14; mean age, 44.4±8.7 years; 93% men) PTSD. They performed polysomnography over 2 nights on all participants, including sleep staging and evaluation of respiratory function, limb movements, and heart rate. The presence of sleep disorders was also assessed.
Patients with PTSD rated their sleep as extremely poor and scored very high on insomnia and nightmares compared with controls (P <.0005 for all). In addition, symptoms of periodic limb movement disorder occurred more often in patients than in controls (P =.026), as did sleep disorder-related daily functioning complaints (P <.0005).
In terms of sleep macrostructure, patients with PTSD displayed significantly more awakenings during sleep (P =.025), increased wake after sleep onset (P =.037), tendency toward longer sleep latency (P =.077), reduced sleep efficiency (P =.025), and increased REM latency (P =.043). Trend level alterations in N1 and N3 sleep percentage composition were also observed.
Sleep electroencephalogram spectral analysis demonstrated a conspicuous pattern of difference between those with PTSD and controls. NREM sleep had a substantial loss of slow oscillation power and increased higher frequency activity in people with PTSD compared with controls. The change was most pronounced over right-frontal sensors, correlating with insomnia (r, -0.46; P =.017). In addition, PTSD REM sleep demonstrated a large power shift in the opposite direction, with increased slow oscillation power over occipital areas, correlating strongly with nightmare activity (r, 0.64; P =.048) and modestly with insomnia (r, 0.50; P =.007).
The study authors suggest that these power changes reflect the hallmarks of PTSD sleep problems and may be specific to the disorder, constituting a biomarker. In comparisons of PTSD and non-PTSD groups, the PTSD group spectral sleep index demonstrated an effect size of 3.4 and correlated with participants scores on the Clinician Administered PTSD Scale (r, 0.60; P =.007). However, limitations of the study included the small sample size as well as the focus on individuals with severe and chronic PTSD.
“A spectral index derived from these data distinguishes patients from controls with high effect size, bearing promise as a candidate biomarker,” the investigators noted.
De Boer M, NijdamMJ, Jongedijk RA, et al. The spectral fingerprint of sleep problems in post-traumatic stress disorder [published online November 8, 2019]. Sleep. doi.org/10.1093/sleep/zsz269