The Effects of Orexin Antagonism on Fear Extinction in PTSD

Starting soon · Phase 4 · Has a placebo group

Conditions studied: Insomnia, PTSD

In brief

PTSD affects approximately 22% of Veterans who have served in Iraq and Afghanistan. Symptoms of PTSD may include re-experiencing, avoidance of trauma reminders, negative thoughts or feelings, and hyperarousal, such as increased startle reactivity and disturbed sleep. Treatments for PTSD are based on fear extinction principles in which individuals are repeatedly exposed a feared cue in the absence of danger, resulting in diminishing physiological reactions, a process believed to underlie recovery from PTSD. Studies suggest that orexin, a wake-promoting neuropeptide, may enhance fear extinction. This study will examine whether suvorexant, a selective orexin-receptor antagonist, will enhance fear extinction in Veterans with PTSD and insomnia. Finding a role for orexins in fear extinction will support the rationale for its further evaluation in the treatment of PTSD. Suvorexant is an accessible, safe medication that has been well-established in treating insomnia. It has outstanding promise for treating common and distressing symptoms in Veterans with PTSD.

Key facts

Study ID

NCT06788522

Run by

VA Office of Research and Development

People needed

40120

Starts

2026-06-01

Expected to finish

2032-06-30

Last updated by the study team

2026-06-02

Who can join

Age: 18 and older, up to 75. Sex: any. Healthy volunteers: not accepted.

You may qualify if…

• (same for Phase 1 and Phase 2):
• men and women
• a history of US military service
• capable of reading and understanding English
• able to provide written informed consent
• Criterion A event meets DSM-5 criteria and occurred during military service, including combat and military sexual trauma
• Chronic full PTSD diagnosis >3 months duration as indexed by CAPS-5 at screening, and CAPS-5 score > 30
• Insomnia indicated by insomnia severity index (ISI) score > 14
• Subjects on non-exclusionary medications, and must be on a stable dose for at least 4 weeks prior to randomization, including Selective Serotonin Reuptake Inhibitors (SSRIs, e.g.,):
• sertraline
• paroxetine
• fluoxetine
• fluvoxamine
• citalopram
• escitalopram
• Serotonin-norepinephrine reuptake inhibitors (SNRIs; e.g.):
• Desvenlafaxine
• Duloxetine
• Levomilnacipran
• Venlafaxine
• For subjects who are in psychotherapy, treatment must be stable for 6 weeks
• Women of child-bearing potential must not be pregnant or have plans for pregnancy or breastfeeding during the study and must use a medically acceptable method of birth control

You may not qualify if…

• Moderate or severe DSM-5 alcohol or cannabis use disorder in the last 3 months
• Mild alcohol use disorder with abstinence of 30 days will be allowed
• Mild marijuana use disorder will be allowed with abstinence for one week prior to participation
• Any other DSM-5 drug use disorder in the last 3 months will be excluded
• Lifetime bipolar disorder I or II, schizophrenia, schizoaffective disorder, obsessive-compulsive disorder, or major depressive disorder with psychotic features
• Exposure to trauma in the last 3 months
• Use of exclusionary antidepressant (trazodone, mirtazapine, doxepin, tricyclics), mood stabilizers (e.g., lithium), antipsychotic medication
• Prominent suicidal or homicidal ideation or any suicidal behavior in the past 3 months on the Columbia Suicide Severity Rating Scale (C-SSRS) or increased risk of suicide that necessitates additional therapy or inpatient treatment
• Pre-existing moderate sleep apnea or positive screen for sleep apnea by type III device (AHI>15) in the absence of adherence to effective treatment (such as CPAP or oral device)
• Night shift work or extreme morning or evening tendencies in order to avoid the impact of circadian factors on subjective and objective sleep measures
• Neurologic disorder or systemic illness affecting CNS function
• Chronic or unstable medical illness, including:
• unstable angina
• myocardial infarction within the past 6 months
• congestive heart failure
• preexisting hypotension or orthostatic hypotension
• heart block or arrhythmia
• chronic renal or hepatic failure
• pancreatitis
• severe chronic obstructive pulmonary disease
• History of severe traumatic brain injury as assessed by the Ohio State University Traumatic Brain Injury Identification Method (OSU-TBI ID)
• Uncorrected hearing impairment
• Mild cognitive impairment assessed by the Montreal Cognitive Assessment (MOCA)
• Pregnancy, breastfeeding and/or refusal to use effective birth control (for women)
• Previous adverse reaction to a hypnotic

Where it is running

• San Francisco VA Medical Center, San Francisco, CA — San Francisco, California, United States
• Ralph H. Johnson VA Medical Center, Charleston, SC — Charleston, South Carolina, United States

Full record on ClinicalTrials.gov

Trial information comes from ClinicalTrials.gov and is refreshed daily. TrialsForMe does not provide medical care and does not run the studies it lists.