Can a gentle brain zapping technique rewire sleep?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: 1. Aged 18 to 65 years old, male or female. 2. Eligibility required an ICD-11 diagnosis of chronic insomnia disorder, determined by investigator-administered clinical interviews (≥3 nights/week for ≥3 months, despite adequate opportunity/conditions for sleep, with daytime distress or functional impairment). 3. Insomnia Severity Index (ISI) total score ≥ 15 at screening or baseline assessment. 4. Patient Health Questionnaire-9 (PHQ-9) and Generalized Anxiety Disorder-7 (GAD-7) total scores both ≤ 9 at screening assessment. 5. Has full civil capacity, is able to proficiently operate a smartphone and wearable sleep band, and can understand and cooperate with clinical scale assessments and neurophysiological examinations. 6. Voluntarily participates, can ensure on-time hospital visits for 10 transcranial temporal interference stimulation (tTIS) sessions over 2 consecutive weeks, and can cooperate with the 1-month longitudinal follow-up. 7. Fully understands the study purpose, intervention procedures, and potential risks, and voluntarily signs the written informed consent form. Exclusion Criteria: 1. Psychiatric conditions: (1) schizophrenia spectrum disorder or bipolar disorder, determined based on participant self-report of prior clinician diagnosis and treatment history and, when feasible, review of available medical records; (2) moderate-to-severe depressive or anxiety symptoms (PHQ-9 ≥ 10 or GAD-7 ≥ 10; either threshold met); (3) current suicidal ideation/behavior or elevated suicide risk as assessed by the investigator. 2. Secondary sleep disorders: Severe obstructive sleep apnea (OSA; AHI ≥ 30), restless legs syndrome (RLS), narcolepsy, or severe circadian rhythm disorders. 3. Epilepsy risk: History of seizures/convulsions or a clear family history of epilepsy. 4. Intracranial metal and implanted electronic devices: Intracranial metal implants (e.g., aneurysm clips, metal stents, repair patches; fixed dental fillings excluded) or implanted electronic devices (e.g., cardiac pacemakers, deep brain stimulators \[DBS\], vagus nerve stimulators \[VNS\]). 5. Medical history (neurologic): Recent craniotomy, severe traumatic brain injury, or organic brain lesions (e.g., brain tumors). 6. Special populations: Pregnant, lactating, or planning pregnancy during the study period. 7. Skin and physical restrictions: Skin damage, infection, or severe rash at the scalp stimulation site (especially over the left DLPFC and the return electrode site), or severe allergy to conductive gel/electrodes. 8. Somatic comorbidities/substance use: Severe cardiac, pulmonary, hepatic, or renal dysfunction, or other conditions deemed by the investigator to potentially affect participant safety or study assessments (e.g., severe alcohol or drug abuse).