Clinical Research Directory

Inclusion Criteria: * Aged 18-65 years, with no gender restriction. * Meet the diagnostic criteria for amphetamine-type stimulant use disorder as defined by the \*Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, Text Revision\* (DSM-5-TR). * Methamphetamine is confirmed as the sole primary substance of use based on rehabilitation records, clinical history interviews and laboratory test data. * Participants are in the abstinence rehabilitation phase. The interval since last methamphetamine use is ≥ 2 weeks, or acute intoxication and acute withdrawal reactions are judged to be substantially stable by investigators. No severe acute intoxication, delirium, or physically/psychiatrically unstable status requiring urgent management occurs within the preceding 2 weeks. * Meet the diagnostic criteria for insomnia disorder, with insomnia symptoms lasting ≥ 3 months and a total Insomnia Severity Index (ISI) score ≥15. * For participants taking antidepressants, anxiolytics, antipsychotics, sedative-hypnotics or other medications potentially affecting sleep or mood, dosages remain stable for at least 4 weeks before enrollment, and no active dose adjustment is allowed during the study. * Voluntarily agree to participate in the study and provide written informed consent. Exclusion Criteria: * The primary substance of use is not methamphetamine, or there exists comorbid use disorders for opioids, ketamine, etomidate, dextromethorphan, alcohol or other major psychoactive substances that, in the investigators' judgment, may substantially confound assessments of sleep, mood, craving or heart rate variability (HRV). * Presence of ongoing acute intoxication, severe acute withdrawal, delirium, or physically/psychiatrically unstable status requiring priority clinical management. * Current severe depression with clear suicidal ideation or plans, urgent clinical risk indicated by the Columbia-Suicide Severity Rating Scale (C-SSRS), or recent severe self-harm or suicidal behavior. * Acute episode of psychotic disorders, manic/mixed episodes of bipolar disorder, severe cognitive impairment, or inability to complete study assessments. * Suspected or confirmed other sleep disorders (including obstructive sleep apnea, narcolepsy, restless legs syndrome, circadian rhythm sleep-wake disorders and parasomnias) that can explain the main insomnia symptoms, as determined by investigators. * Severe arrhythmia, marked bradycardia, decompensated cardiopulmonary disease, severe hepatic or renal insufficiency, epilepsy, or other neurological diseases deemed unsuitable for electrical stimulation. * Implanted electronic devices, such as cardiac pacemakers, implantable cardioverter-defibrillators, cochlear implants, or other electronic hardware susceptible to electrical stimulation interference. * Bilateral ear stimulation target areas with skin breakdown, infection, severe eczema, scarring, or other auricular diseases that prevent safe electrode clamping. * Pregnant or breastfeeding women, or women who plan to become pregnant during the study. * Participation in other interventional clinical trials or receipt of other neuromodulation therapies within 1 month before enrollment. * Any other conditions that may affect safety, adherence or primary outcome evaluation at the discretion of investigators. * Meet the diagnostic criteria for insomnia disorder, with insomnia symptoms persisting for ≥ 3 months and a total ISI score ≥ 15; * For participants taking antidepressants, anxiolytics, antipsychotics, sedative-hypnotics or other medications that may affect sleep or mood, the dosage must have been relatively stable for 4 weeks prior to enrollment, and no proactive dose adjustment will be performed during the study period; * Voluntarily participate in this study and provide written informed consent.