This is a research study to find out if mental health symptoms in patients admitted to the Institute of Psychiatry are affected by a form of ear stimulation called transcutaneous auricular vagus nerve stimulation, or taVNS. Participants will receive ear stimulation during their inpatient treatment at the Institute of Psychiatry. Participants will be randomly assigned to either receive ear stimulation for 1 day (up to 9 treatments over the course of a single day) or 3 days (up to 3 treatments per day), and will have a 50:50 chance of being in either group (like the flip of a coin). Each treatment will last up to 30 minutes and there will be a break of at least 30 minutes in between treatments. The study team will ask participants to complete a group of questionnaires at the beginning and end of the study. In addition, there are several questionnaires that will be completed daily while participants are receiving ear stimulation. Participants in the 1 day stimulation group will also receive 2 days of follow up questionnaires after the initial day of stimulation. The questionnaires will ask questions about mental health symptoms that subjects may or may not be experiencing, including questions about mood, anxiety, and sleep. The ear stimulation treatments will not interfere with the care subjects are receiving from the medical team. In order to qualify for this study, participants must be actively receiving inpatient care at the MUSC Institute of Psychiatry.

Inclusion Criteria:

• Ages 18 and up
• English speaking
• Admitted to 3 North's inpatient unit in MUSC's Institute of Psychiatry (IOP)
• Have the capacity and ability to provide one's own consent and sign the informed consent document
• Primary depression diagnosis

Exclusion Criteria:

• Facial or ear pain or recent ear trauma.
• Metal implant devices in the head, heart or neck.
• History of brain surgery.
• History of myocardial infarction or arrhythmia, bradycardia.
• Acute exacerbation of a chronic respiratory disorder or acute COVID-related symptoms.
• Active GI symptoms with a history of diabetes mellitus or history of gastroparesis secondary to diabetes mellitus.
• Personal or family history of seizure or epilepsy or personal use of medications that substantially reduce seizure threshold (e.g., olanzapine, chlorpromazine, lithium).
• Personal history of head injury, concussion, or self-report of moderate to severe traumatic brain injury.
• Individuals suffering from frequent/severe headaches.
• Individuals with a reported history of psychosis or mania, or individuals who are actively manic or psychotic.
• Individuals who are catatonic or otherwise unable to participate in the informed consent process.
• Moderate to severe alcohol or substance use disorder.
• Pregnancy