This project aims to use sensors to monitor physiological signals, sleep patterns, vocal characteristics, activity, location and phone usage in study patients with depression who are receiving standard treatment (compared with healthy controls).

Inclusion Criteria:

Patients with Depression (n=40):

1. Adults (ages 18-75),
2. Able to read, understand, and provide written informed consent in English,
3. Meet criteria for a primary psychiatric diagnosis of major depressive disorder for ≥ 4 weeks, according to the M.I.N.I (Mini International Neuropsychiatric Interview),
4. Hamilton Depression Rating Scale (HDRS) total score ≥ 18,
5. Engaged in or willing to be referred for clinical care for depression treatment as usual (antidepressants and/or psychotherapy),
6. Must have measurable skin conductance/electrodermal activity (as assessed at the screening visit),
7. Must own a working Android smartphone (Android 2.3+) and use it regularly,
8. Must own a windows PC (or tablet) or a Mac computer (or laptop),
9. Must have access to Internet service every day.

Healthy Controls (n=10):

1. Adults (ages 18-75),
2. Able to read, understand, and provide written informed consent in English,
3. Not meet criteria for past or current psychiatric illness, excluding specific phobias, as measured by the M.I.N.I.,
4. Not have a first-degree relative with known major psychiatric illness including Major Depressive Disorder, Bipolar Disorder, Psychotic Disorder or Substance Use Disorder,
5. Must have measurable skin conductance/electrodermal activity (as assessed at the screening visit),
6. Must own a working Android smartphone (Android 2.3+) and use it regularly,
7. Must own a windows PC (or tablet) or a Mac computer (or laptop),
8. Must have access to Internet service every day.

Exclusion Criteria (for all subjects):

1. Active drug or alcohol use disorder in the past 3 months,
2. History of psychosis,
3. History of mania or hypomania,
4. Epilepsy or history of seizures,
5. Untreated hypothyroidism,
6. Unstable medical disease,
7. Cognitive impairment that would impede adherence to study procedures,
8. Acute suicide or homicide risk,
9. Current treatment with electroconvulsive therapy, vagal nerve stimulation therapy, deep brain stimulation, transcranial magnetic stimulation therapy, or phototherapy,
10. Concurrent participation in other research studies,
11. Cannot comprehend or communicate in English,
12. Lack of working smartphone or lack of daily access to Internet service,
13. Inability to measure skin conductance/electrodermal activity (as assessed at the screening visit), and
14. Inability or unwilling to, at minimum, wear the physiological sensor (E4) bands, fill out the surveys, and record a weekly diary.

Adult outpatients with a current major depressive episode (n=40) and healthy adult controls (n=10).