Inclusion Criteria:  Male and female GW Veterans between the ages of 48-80 Deployed to the "Gulf Theater of operations," as defined by 38 CFR 3.317 Meets the Kansas GWI and Centers for Disease Control and Prevention (CDC) Chronic Multisymptom Illness (CMI) case definitions. The Kansas GWI definition requires cases to endorse multiple or moderate-to-severe chronic symptoms in at least three of six symptom domains. These include: i) fatigue/sleep problems, ii) somatic pain, iii) neurological cognitive, mood symptoms, iv) gastrointestinal symptoms, v) respiratory symptoms, and vi) skin abnormalities. Veterans will be excluded from being considered Kansas GWI cases, for purposes of the proposed trial, if they report being diagnosed by a physician with medical or psychiatric conditions that would account for their symptoms or interfere with their ability to report their symptoms. Veterans with current or past history of PTSD or depression in the past 5 years will not be excluded from participation if they have not been hospitalized for these conditions. The CDC CMI case definition requires cases to endorse symptoms in at least two of three symptom clusters. These include: i) fatigability (e.g., feeling fatigue for 24 hours or more after exertion), ii) mood/cognitive symptoms (e.g., feeling depressed, irritable, worried, tense or anxious; difficulty thinking or concentrating, problems finding words, or problems getting to or staying asleep). iii) musculoskeletal pain. Meet the DSM-5 research diagnostic criteria for insomnia disorder. Unlike other GWI symptoms, we will not require the Veteran's insomnia to have begun during the Gulf War or within one year after leaving the Gulf region. This is because some GWI symptoms may cause veterans to adopt behaviors that lead to sleep problems later. Results from our CBT-I trial in Veterans with GWI suggest that improving sleep also improves non-sleep related symptoms such as fatigue, depression, pain, and psychosocial function. Therefore, we hypothesize that even if insomnia was not one of the original GWI symptoms, improving sleep in veterans with GWI will also improve other GWI-related symptoms. Diagnosed with obstructive sleep apnea (OSA) by physician based on polysomnography or evidence of OSA based on an Apnea-Hyponea Index (AHI) or respiratory disturbance index (RDI) that is > or = 5 based on home sleep apnea testing. Have access to wireless internet connection at home for remote positive airway pressure (PAP) data capture.  Exclusion Criteria:  Condition(s) that is/are considered exclusionary for the Kansas GWI criteria. For purposes of this trial, this will include medical or psychiatric conditions diagnosed by a physician/psychiatrist that would account for the Veterans' symptoms or interfere with their ability to report their symptoms. Specific exclusionary criteria include medical conditions such as uncontrolled diabetes, heart disease other than hypertension, stroke, lupus, multiple sclerosis, cancer, liver disease, chronic infection, or serious neurological condition (e.g., dementia, brain injury). History of any psychiatric disorder with active psychosis or mania in the past 5 years. Severe drug or alcohol use disorder within the past 6 months as assessed by the Structured Clinical Interview for DSM-5 (SCID 5). Veterans with moderate drug or alcohol use disorder will be reviewed on a case-by-case basis. Prominent suicidal or homicidal ideation. Pregnancy, because insomnia will worsen after 8 weeks. Restless Legs Syndrome (RLS) or screening indicative of RLS based on Restless legs syndrome screening questionnaire (RLSSQ). Current enrollment in another clinical trial. Traumatic brain injury (TBI) will not be exclusionary for the proposed study unless it impacts cognition to a degree that the Veteran cannot complete treatment or homework assignments (this will be determined on a case-by-case basis at PI and therapists' discretion). Starting or ending psychotherapy for a sleep disorder or mental health diagnosis within the last one month. Starting or ending an antidepressant, anxiolytic, or sleep medication with the last one month will be excluded. Veterans currently receiving benzodiazepine or benzodiazepine receptor agonists, anticonvulsants, atypical antipsychotic medication, or non-SSRI antidepressant medications such as trazodone will be not be excluded provided that they meet the DSM-5 criteria for insomnia disorder, exhibit evidence of OSA, and will remain on the medication(s) throughout the 6-week treatment period and the 3-month follow-up period.