HALO Clarity™ Cranial Alternating Current Stimulation Therapy for Adults With Moderate-to-Severe Insomnia

Inclusion Criteria Participants must meet all of the following criteria to be eligible for the study: * Provide written informed consent prior to any study-related procedures. * Age between 22 and 65 years, inclusive. * Total score on the Insomnia Severity Index (ISI) of ≥15 at screening, indicating moderate-to-severe insomnia. * Participant-reported diagnosis of insomnia, confirmed by a licensed clinician during the remote clinical evaluation call. * Willingness to be randomized to either the active or sham device arm. * Agreement not to use any sleep tracking devices or applications (e.g., smartwatches, sleep apps) during the study. * Ability to read and write English at an 8th-grade level or higher. * Ability to receive packages at home via standard delivery services (United States Postal Service, FedEx, or UPS) in all U.S. states except Alaska and Hawaii. * Willing and able to use a personal internet-capable mobile device throughout the study for completing questionnaires, using the HALO Clarity™ App, and receiving study-related text messages. * Owns and is willing to communicate using a personal, verifiable email address. * Able and willing to commit to one 40-minute treatment session using the HALO Clarity™ device, 5 days per week for 4 weeks (up to 20 sessions total). * If currently using sleep medication, the regimen must have been stable for at least the past 3 months, with willingness to maintain the same medication and dosage throughout the study (no new sleep medications may be started during the trial). Exclusion Criteria Participants who meet any of the following criteria will be excluded from the study: * Presence of a current medical condition that, in the opinion of the Investigator or delegate, could impair reliable participation in the study or require the use of prohibited medications. * Use of any form of electronic brain stimulation or neuromodulation within the past 1 year (including cranial electrotherapy stimulation \[CES\], transcranial magnetic stimulation \[TMS\], electroconvulsive therapy \[ECT\], or deep brain stimulation). * Institutionalization for a mental health condition within 1 year prior to study entry. * Current or history of alcohol or drug abuse or dependence within the past 5 years. * Under medical supervision for a serious medical condition (including, but not limited to, intracranial tumors or aneurysm). * Suspected or known history of heart disease. * Implanted electronic device (e.g., pacemaker, defibrillator, deep brain stimulator, or cochlear implant). * History of seizures or epilepsy. * History or current diagnosis of a chronic pain condition and/or use of opioids for any reason within the past 3 months. * Use of recreational drugs, hypnotics, anabolic steroids, or marijuana products within the past 30 days, or planned use during the study (stable use of CBD is permitted). * Females who are currently pregnant or planning to become pregnant during study participation. * Current participation in another investigational study, or participation in an investigational study within the past 30 days. * Any other condition or circumstance that, in the opinion of the Investigator, would make the participant unsuitable for the study.