Phenotype Depression Study

One hundred and thiry-five patients with major depression diagnosed based on DSM-IV TR criteria between the ages of 21 and 65 (males, females and minorities) will be recruited. Forty-five patients with high inflammation as defined by a CRP \>3 mg/L will be enrolled along with 45 depressed patients with medium inflammation (CRP=1-3mg/L) and 45 depressed patients with low inflammation (CRP\<1mg/L) will complete a 2 night inpatient stay in Emory University Hospital's research unit, the Atlanta Clinical and Translational Science Institute (ACTSI). Participants will undergo psychiatric and neurocognitive assessments, sleep studies and blood and cerebral spinal fluid (CSF) sampling.