Impact of GHRH on Sleep Promotion and Endocrine Regulation in Service Members Who Sustained a Traumatic Brain Injury and Have Current Insomnia

* INCLUSION CRITERIA: Both groups may be eligible for this research study if they: 1. Are between 18 and 45 years of age (on Visit 1) 2. Are active duty service members or veterans who were active duty within the past 10 years (on Visit 1) 3. Are able to provide medical records documenting a TBI, which occurred within the past 6 months to 10 years (on Visit 1) 4. Are able to provide their own consent 5. Are able to understand the study, as shown by scoring a 6 out of 6 on a consent quiz 6. (For women only) agree not to breastfeed from the time of enrollment in the study until 1 month after the last exposure to tesamorelin 7. (For women of childbearing potential only) have a negative urine pregnancy test and agree to use two effective methods of contraception from the time of enrollment in the study until 1 month after the last exposure to tesamorelin The insomnia group may be eligible for this research study if they: 1. Have a current clinical diagnosis of insomnia determined by polysomnography 2. Have a PSQI score greater than 10 The no-insomnia group may be eligible for this research study if they: 1. Have no current clinical diagnosis of insomnia determined by self-report 2. Have a PSQI score less than or equal to 5 EXCLUSION CRITERIA: Both groups may not be eligible for this research study if they: 1. Have obstructive sleep apnea determined by polysomnography (insomnia group) or selfreport (no-insomnia group) 2. Have a known hypersensitivity to tesamorelin and/or mannitol 3. Have taken any of the following medications within the past 30 days: benzodiazepines (e.g., Valium, Ativan, etc.); benzodiazepine receptor agonists (e.g., Ambien, Lunesta, etc.); opiates (e.g., Codeine, Percocet, etc.); or sedatives (e.g., Amytal, Numbutal, etc.) 4. Cannot abstain from using stimulants such as amphetamines (e.g., Adderall, Ritalin, etc.); caffeine (e.g., coffee, cola, etc.); ephedrine (e.g., diet pills, energy drinks, etc.); and eugeroics (e.g., Modafinil, Provigil, etc.) from at least 9:00 AM on Visits 2 and 3 5. Are under treatment for a major injury (e.g., amputation, burns, eye injury, skeletal injury, severe infection, etc.) 6. Have a major medical illness (e.g., active malignancy, cardiovascular disease, diabetes mellitus, HIV, etc.) 7. Are at risk for self-harm determined by a licensed independent practitioner 8. Have indications of recreational substance use determined by a urine drug test 9. Have an abnormal lab value that may indicate major medical illness, which was not cleared by a licensed independent practitioner 10. Have an abnormal lab value that may indicate endocrine dysfunction, which was not cleared by a licensed independent practitioner 11. Have adrenal insufficiency determined by the ACTH stimulation test 12. Have a current bipolar disorder determined by the SCID-IV-TR 13. Have a current psychotic disorder determined by the SCID-IV-TR 14. Have current alcohol dependence determined by the SCID-IV-TR 15. Have current drug dependence determined by the SCID-IV-TR