This two-part study seeks to improve symptoms such as pain and sleep problems after concussion, or mild traumatic brain injury (mTBI).

Study I evaluates symptoms of mTBI through a series of 10 office sessions in which musical tones are echoed, or mirrored back in real time, to reflect one's own brain activity. Those who take part in the study will be randomly assigned to receive either tones that are based on their brain activity/brainwaves, or random tones.

Study II evaluates symptoms of mTBI through either 10 office sessions of the same acoustic stimulation linked to brain activity/brainwaves as Study I compared to 5 office sessions of acoustic stimulation plus intermittent very low level electrical stimulation of the scalp linked to brain activity.

Persistent symptoms after concussion or mild traumatic brain injury (mTBI), such as pain and sleep difficulties, may be related to altered patterns of brain electrical activity, including changes in amplitude and frequency. The purpose of these two studies is to evaluate a noninvasive, closed-loop, acoustic stimulation neurotechnology, High resolution, relational, resonance-based, electroencephalic mirroring, with standard operating procedures, HIRREM-SOP. This intervention is intended to improve symptoms by supporting self-optimization of brain electrical activity. Put more simply, musical tones will be played to echo, or mirror one's own brainwaves, in real time, allowing opportunity for auto-calibration, self-adjustment, and equilibration of that brain activity. The hypothesis is that over the course of ten 90-minute sessions, symptoms related to mTBI, will improve much more with musical tones linked to brainwaves than with random tones.

Participants will be enrolled at Uniformed Services University/Walter Reed National Military Medical Center in Bethesda, MD, and Womack Army Medical Center, Fort Bragg, NC.

The 106 participants in the first part of the study can be active duty or recently retired service members, or their family members, who have had a mTBI at least three months and not more than ten years ago, with related symptoms. Participants will be randomized to either musical tones that reflect their own brain activity, or random tones. A technologist will oversee each session in which the tones are presented. Participants and those analyzing outcomes will be blinded to the nature of the acoustic stimuli received. The primary outcome will be the change in Neurobehavioral Symptom Inventory scores at three months, and the final follow-up will occur be at six months. Changes in sleep, pain, dizziness, and general quality of life will also be measured.

Study II will recruit up to 100 participants with the goal of randomizing 86 participants to one of the two interventional arms equally across the same locations with the same inclusions criteria. This study seeks to establish a non-inferiority for the shorter course intervention. The primary outcome measure will continue to be the NSI score measured post-intervention and at 3-months. Changes in sleep, pain, dizziness, and general quality of life will also be measured.

Inclusion Criteria:

• 1 Must have symptoms related to concussion or TBI, not healthy controls Age 18 years or older.
• 2 Active duty or retired military service member, or dependent beneficiary.
• 3 History of mild TBI, confirmed by administration of the Ohio State University TBI
• Identification Method Interview.
• 4 At least three months, and no more than ten years, since their most recent TBI.
• 5 Persistent symptoms temporally related, or otherwise attributable to, the TBI, such as
• headache or chronic pain, sensory disturbance including auditory, visual or other sensory
• symptoms, balance difficulties, or dizziness. After obtaining informed consent, sufficient
• severity of symptoms for entry into the study will be confirmed by administration of the
• Neurobehavioral Symptom Inventory (NSI), with a score of 23 or higher required for
• inclusion.
• 6 Willingness to be randomly assigned to one of the two treatment groups and to provide
• data for all study measures.
• 7 Willingness to abstain from alcohol or recreational drug use throughout the intervention
• period and up to 3 weeks after completion of the final office-based intervention session.
• This abstention period is intended to support the stabilization of new brain activity
• patterns that may result from the intervention.
• 8 For individuals using any of the following medication classes (either regularly scheduled
• or PRN), a willingness both to discontinue or hold those medications at least five (5) halflives
• prior to the initiation of study procedures, and throughout the period of participation
• in the study, as well as to sign a release enabling contact between study staff and their
• prescribing provider, to ensure that the prescriber deems that holding said medication
• during the study period is permissible and reasonable: benzodiazepines, opioids, antipsychotics,
• mood-stabilizers, anti-convulsants, non-benzodiazepine sleep aids (including
• but not limited zolpidem, eszoplicone, zaleplon, trazadone, and diphenhydramine), other
• prescribed sedative-hypnotics, or medical marijuana or cannabinoid medication.
• 9 Willingness to abstain from initiation of PRN/as needed usage of the above listed
• medications throughout the period of study participation. This criterion only applies to
• new PRN prescription or usage. There is no requirement to abstain from a new, regularly scheduled prescription for one of the above medications during the course of the study, if the participant's provider
• deems such usage to be indicated. The potential impact of the initiation of any such
• medications during the study will be assessed by conducting sensitivity analyses after the
• completion of the study.
• 10 Willingness to alert study investigators of any changes in their medication usage
• throughout the course of their study participation.

Exclusion Criteria:

• 1 Unable or unwilling to demonstrate an understanding of the nature and intent of the
• study, and/or to complete informed consent procedures.
• 2 A history of moderate or severe TBI.
• 3 The diagnosis of a psychotic disorder (including schizophrenia and schizoaffective
• disorder), severe depression (PHQ-9 score > 20), bipolar disorder, or active suicidal or
• homicidal ideation.
• 4 Physically unable to come to the study visits, or to sit in a chair for up to two hours.
• 5 Inability to hear and repeat a phrase spoken at normal conversational volume.
• 6 Meeting criteria for a current alcohol or substance use disorder.

Study I - Single-blind (participants and outcomes assessors blinded, but technologists are not), up to 126 enrolled (target of 106 being randomized)

Study II - Controlled (participants randomly assigned to one of two interventional arms, no blinding due to 5 or 10 sessions), up to 110 enrolled (target of 86 being randomized)