Inclusion Criteria:
* Be aged ≥ 18 to ≤ 70 years
* Have a history of concussive TBI ≥ 3 months prior to enrollment:
* A concussive TBI is defined by having at least one of the following after a head trauma (ACRM, 1993) oAny period of loss of consciousness; oAny loss of memory for events immediately before or after the accident; oAny alteration in mental state at the time of the accident (e.g., feeling dazed, disoriented, or confused); and oFocal neurological deficit(s) that may or may not be transient oThe injury must not exceed any of the following (ACRM, 1993):
* Loss of consciousness of approximately 30 minutes or less;
* After 30 minutes an initial GCS score of 13-15; and
* PTA not greater than 24 hours
* Head trauma resulting in concussive TBI can be due to blast or non-blast mechanisms
* Head trauma resulting in concussive TBI can have occurred any time in the participant's life: prior to military service, during deployment, in garrison, or after leaving military service
* Have a history of chronic PTH defined as:
o Headache is reported to have developed (or worsened) after one of the following\*:
* The injury to the head;
* Regaining of consciousness following the injury to the head; or
* Discontinuation of medication(s) impairing ability to sense or report headache following the injury to the head
* Not better accounted for by another ICHD-3 diagnosis\*\*
o The headache persists for \>3 months after its onset (ICHD, 2013)
* Have a HIT-6™ score of ≥ 56 to 78 indicative of substantial impact (56-59) or severe impact (60-78) on functioning (Yang, Rendas-Baum, Varon, \& Kosinski, 2011)
* Be able to provide written, informed consent in English and follow study-related instructions
* Have ownership of or reliable access to a smartphone with a data plan or internet connecting capabilities
* Be aged ≥ 18 to ≤ 70 years
* Have a history of concussive TBI ≥ 3 months prior to enrollment:
* A concussive TBI is defined by having at least one of the following after a head trauma (ACRM, 1993):
* Any period of loss of consciousness;
* Any loss of memory for events immediately before or after the accident;
* Any alteration in mental state at the time of the accident (e.g., feeling dazed, disoriented, or confused); and
* Focal neurological deficit(s) that may or may not be transient
* The injury must not exceed any of the following (ACRM, 1993):
* Loss of consciousness of approximately 30 minutes or less;
* After 30 minutes an initial GCS score of 13-15; and
* PTA not greater than 24 hours
* Head trauma resulting in concussive TBI can be due to blast or non-blast mechanisms
* Head trauma resulting in concussive TBI can have occurred any time in the participant's life: prior to military service, during deployment, in garrison, or after leaving military service
* Have a history of chronic PTH defined as:
o Headache is reported to have developed (or worsened) after one of the following\*:
* The injury to the head;
* Regaining of consciousness following the injury to the head; or
* Discontinuation of medication(s) impairing ability to sense or report headache following the injury to the head
* Not better accounted for by another ICHD-3 diagnosis\*\*
o The headache persists for \>3 months after its onset (ICHD, 2013)
* Have a HIT-6™ score of ≥ 56 to 78 indicative of substantial impact (56-59) or severe impact (60-78) on functioning (Yang, Rendas-Baum, Varon, \& Kosinski, 2011)
* Be able to provide written, informed consent in English and follow study-related instructions
* Have ownership of or reliable access to a smartphone with a data plan or internet connecting capabilities
Exclusion Criteria:
* They experienced a moderate or severe TBI
* Their secondary headache is better accounted for by the ICHD-3 diagnosis of 8.2 medication-overuse headache; must meet diagnostic criteria for at least 1 medication-overuse headache diagnosis (8.2.1-8.2.8)
* They are currently engaged in psychotherapeutic treatment or have engaged in psychotherapeutic treatment within 8 weeks prior to trial enrollment (for more information regarding recent treatment in potential participants, see section '3.2 Study Procedures,' sub-section 'Baseline Evaluation')
* They report change or discontinuation of headache prophylaxis in the past 4 weeks
* They report active psychotic or bipolar symptoms
* In the opinion of the investigator, they have other considerations that may adversely affect patient safety, participation, or scientific validity of the data being collected (including, but not limited to, active plan or intent for suicide, visual impairment, hand dysfunction or amputation, substantial cognitive impairment, life expectancy of less than 6 months)
