Inclusion Criteria:
* diagnosed with sleep onset insomnia
* Self report insomnia diagnosis (ISI score ≥15)
* 18-70 years old that are Tricare eligible
* No pharmacologic or non-pharmacologic treatment for insomnia in the last 14 days, including over-the-counter medications such as diphenhydramine or cyclobenzaprine not using sedating medications (including over-the-counter) at bedtime in the last 14 days. These can include sedating antihistamines such as diphenhydramine/Benadryl, combination pills such as Tylenol or Advil PM, ZzzQuil. Psychiatric medications such as benzodiazepines (clonazepam/Klonopin, lorazepam/Ativan, diazepam/Valium, alprazolam/Xanax), anti-histamines (hydroxyzine/Atarax/Vistaril), or anti-psychotics (quetiapine/Seroquel).
Exclusion Criteria:
* Neurologic conditions such as seizures or conditions that increase the risk of seizures, including concussions within the last 3 months; moderate or severe traumatic brain injury; stroke; multiple sclerosis; or cognitive impairment with or without the use of prescription medication or requirement for hospitalization.
* Any psychiatric disorder requiring weekly or more frequent clinical monitoring or medication changes in the last 4 weeks.
* History of neurodevelopmental disorder such as attention deficit hyperactivity disorder, learning disability, or developmental delay
* Any inpatient hospitalization, major surgery, or medical procedure within the past 6 months
* Hearing impairments requiring implanted or external devices worn at all times for amplification.
\*\*Pregnant or believes there is a chance of pregnancy
* Current substance use disorder (addiction) within the past year, not including nicotine Current use of narcotics (opioid based medications for the treatment of pain (OxyContin, Percocet, Vicodin, etc.) with or without a prescription within the last year
* Change in psychotropic (non sleep related) medications within the last 4 weeks (examples include: benzodiazepines, SSRI/SNRIs, bupropion, gabapentin).
* Consuming more than 10 alcoholic beverages per week
* Treatment for drug or alcohol use/abuse within the past 1 year
* Presence of a recently diagnosed or unstable sleep disorder, other than insomnia, with an treatment regimen less than 3 months old
* Any motor coordination deficits that interfere with use of the tES device
* Participants should not have trauma/cuts/rashes to their forehead or behind the ears that would interfere with wearing of the device or cause discomfort for the research subject
* Tattoos on the head
* Non-removable metal above the shoulders, except bridges or fillings, OR implanted devices anywhere in the body (e.g., pacemakers, defibrillators, cochlear implants, brain implants including deep brain stimulators or other implanted devices) presence of an unstable medical condition that significantly contributes to their insomnia (e.g. chronic pain, cough, GERD, sleep apnea) - or diagnosis of an above condition that no longer significantly contribute to insomnia but has not been stable on a treatment regimen for at least 3 months.
any suicidal attempts within the last 12 months.
* Any other condition that the investigator believes would prevent completion of the study or put participant at risk
* Any suicidal ideations or thoughts of self-harm (as measured by the PHQ-9, Item 9) within the last 2 weeks.
* Note: Pregnancy Safety data for tES use in pregnant women is scarce but is reviewed in: Antal, Andrea, et al. "Low intensity transcranial electric stimulation: safety, ethical, legal regulatory and application guidelines." Clinical neurophysiology 128.9 (2017): 1774-1809. The authors cite two case studies of tES use in pregnant women with no impact or safety risk for the mother or fetus when tES was applied to the head at 2mA and 20-30 min per day. The recommendation by the authors is to verbally enquire as to the pregnancy status of the subjects and only deliver tES when the benefit outweighs risk. Here we propose to completely exclude this population if the questionnaire reveals they are pregnant or are trying to become pregnant. In the event that the patient is untruthful regarding their pregnancy status we view the risk as insignificant given these reported studies and the fact that our dose is \<¼ the dose used in them. For this reason we have chosen not to perform a urine test to screen for pregnancy as we view it as an obtrusive and unnecessary step given the risk profile.
