Sleep/Wake Cycle and Depression: An Imaging and Treatment Study

Inclusion criteria for depressed and non-depressed individuals * Consent form signed * Capacity to give informed consent * Age 18 years or older (inclusive) * Diagnosis of MDD and currently in a major depressive episode (depressed participants only) * Score of at least twenty-nine on the MADRS (depressed participants only) Exclusion Criteria: * Participant considered at significant risk for suicide * Unlikely to tolerate medication washout or the drug free period following washout (depressed participants only) * Current psychosis * ECT within 4 weeks of the first overnight visit * Significant active physical illness or neurological deficit that may affect brain function or imaging * A disease, job or life circumstance that creates an irregular circadian rhythm anticipated during the study * Inability to maintain in bed and out of bed (regardless of sleep time, for depressed individuals) or sleep and wake times (for non-depressed individuals) to within \~30 min for a week before each overnight visit (will be measured by actigraphy and/or other measurements) * Inability to abstain from medications that will affect glutamate levels or circadian rhythms, including stimulants, anti-epileptics, antidepressants, beta-blockers, hypnotics (including benzodiazepines), melatonin, or medications with glutamateric or GABAergic modes of action within 4 weeks before the first overnight visit as well as throughout the study * Inability to reduce caffeine intake to \<= \~300 mg of caffeine…