Research Paper Title

Increased Oscillatory Frequency of Sleep Spindles in Combat-Exposed Veteran Men with Post-Traumatic Stress Disorder.

Background

Sleep disturbances are core symptoms of post-traumatic stress disorder (PTSD), but reliable sleep markers of PTSD have yet to be identified.

Sleep spindles are important brain waves associated with sleep protection and sleep-dependent memory consolidation.

The present study tested whether sleep spindles are altered in individuals with PTSD and whether the findings are reproducible across nights and sub-samples of the study.

Methods

Seventy-eight combat-exposed veteran men with (n = 31) and without (n = 47) PTSD completed two consecutive nights of high-density EEG recordings in a laboratory.

The researchers identified slow (10-13 Hz) and fast (13-16 Hz) sleep spindles during N2 and N3 sleep stages and performed topographical analyses of spindle parameters (amplitude, duration, oscillatory frequency, and density) on both nights.

To assess reproducibility, they used the first 47 consecutive participants (18 with PTSD) for initial discovery and the remaining 31 participants (13 with PTSD) for replication assessment.

Results

In the discovery analysis, compared to non-PTSD participants, PTSD participants exhibited 1) higher slow-spindle oscillatory frequency over the antero-frontal regions on both nights and 2) higher fast-spindle oscillatory frequency over the centro-parietal regions on the second night.

The first finding was preserved in the replication analysis.

The researchers found no significant group differences in the amplitude, duration, or density of slow or fast spindles.

Conclusions

The elevated spindle oscillatory frequency in PTSD may indicate a deficient sensory-gating mechanism responsible for preserving sleep continuity.

The findings, if independently validated, may assist in the development of sleep-focused PTSD diagnostics and interventions.

Reference

Wang, C., Laxminarayan, S., Ramakrishnan, S., Dovzhenok, A., Cashmere, J.D., Germain, A. & Reifman, J. (2020) Increased Oscillatory Frequency of Sleep Spindles in Combat-Exposed Veteran Men with Post-Traumatic Stress Disorder. Sleep. pii: zsaa064. doi: 10.1093/sleep/zsaa064. [Epub ahead of print].