Comparing Acoustic Resonance Therapy (ART) vs. Cognitive Behavioral Therapy for Insomnia (CBT-I)

Inclusion Criteria: * Adult subjects, 22 years of age and older at screening * Moderate-to-severe insomnia disorder, as defined by the International Classification of Sleep Disorders (ICSD-3)\* and the Insomnia Severity Index (ISI) and have been diagnosed for more than three months. * Not pregnant by subject self-report at time of consent. * Have the ability to provide informed consent. * Have the ability to complete all aspects of this trial. * Have access to an iOS mobile device (iPhone X or above). * Have no contraindicating comorbid health condition that would interfere with the proper use of the SONU Headband system, as determined by the clinical investigators. * Participants who are taking sleep-aiding pills must agree to no changes to medication and dosage during the study. * According to the third edition of the International Classification of Sleep Disorders (ICSD-3), insomnia is characterized by difficulty in either initiating sleep, maintaining sleep continuity, or poor sleep quality Exclusion Criteria: * Patients who are unable to commit to avoiding the consumption of alcohol during the study. * Patients who are unable to commit to avoid consumption of caffeine after 12 pm (noon). * Patients who have a clinically significant or unstable medical or surgical condition. * Participants using pacemakers or cardiac monitors. * Participants with severe physical illness or immediately post-surgery * Participants with severe mental disorders, such as schizophrenia, severe major depression, severe anxiety, bipolar disorder, dementia, substance use disorder, or severe neurological diseases such as a seizure, stroke, or Parkinson's disease. * Participants with other serious sleep disorders, such as severe obstructive sleep apnea. * Participants who are unable to attend regular follow-up evaluations. * Any unstable medical or mental health condition as determined by the physician investigator.