Specific Aim #5: To examine the predictive value of HRV on outcomes of Immediate MYT+TAU and Delayed MYT + TAU. Hypothesis #5. Increases in high frequency HRV (HF-HRV) from resting baseline to guided meditation at the pre-treatment assessment (week 0 for the immediate MYT treatment group, week 12 for the delayed MYT treatment group) will be associated with greater PTSD symptom reduction at post-treatment (week 12 for the immediate MYT treatment group; week 24 for delayed MYT treatment group).