Inclusion Criteria:  Age 18-60 years Normal or corrected to normal visual acuity, normal hearing Index event that meets DSM-5 PTSD stressor criterion A, viz. "The person was exposed to death, threatened death, actual or threatened serious injury, or actual or threatened sexual violence" by direct exposure, witnessing in person, or having a close relative or friend exposed to violent or accidental actual or threatened death. Self-report of at least 1 nightmares per week related to the index trauma. The trauma nightmares must contain veridical (vs., symbolic, interpreted, etc.) content that is reminiscent of the index trauma. Individuals who meet criteria for at least three of the four DSM-5 criterion categories. At least one recorded nightmares related to the index trauma with at least one suitable for creating a script for SDI.  Exclusion Criteria:  Lifetime history of psychosis, bipolar disorder, autism spectrum or other neurodevelopmental disorder, active risk to self or others History of sleep apnea or an apnea/hypopnea index of >15 on the diagnostic night of ambulatory PSG (i.e., 15 or more sleep apnea-hypopneas per hour of sleep) Neurologic conditions that could confound outcome variables, including past neurosurgical procedures, seizure, neurodegenerative disease, stroke, known structural brain lesion, significant head trauma with extended loss of consciousness and/or persistent neurological sequela (mild TBI allowed) Medical conditions that could confound outcome variables such as severe cardiovascular or other systemic disease Use of benzodiazepines, beta blockers, prazosin or antipsychotics (antidepressants or mood stabilizers with stable dose for ≥ 3 months allowed) Current Alcohol and Substance Use Disorder or positive urine toxicology screen for drugs of abuse MRI contraindications (e.g., metal in body or eyes, pacemaker, pump, stimulator, shunt, claustrophobia, weight >250 lbs.) Pregnancy, breastfeeding or nursing: A pregnancy test (urine ß-HCG) will be conducted prior to the structural MRI for all women of child-bearing capacity Supervisees of study investigators