Neurobiological Effects of Light on MDD

Inclusion Criteria: 1. Able to provide informed consent before beginning any study-specific procedures 2. Male and female patients at least 18-60 years of age 3. Women with reproductive potential must have a negative pregnancy test; 4. Meets DSM-IV criteria for Major Depressive disorder 5. Hamilton Depression Rating Scale total score of 15 or greater 6. Negative Drug screen for drugs of abuse 7. No sleep altering medications, including herbal preparations. If subjects previously taking any of these medications, they need to be 1 week off of medications before starting the study. 8. If currently on SSRI, subjects must have been on them for 6-8 weeks. 9. PSQI of \>5 and without sleep difficulties unrelated to the depression Exclusion criteria: MDD subjects will be excluded if: 1. Subjects with a comorbid current primary Axis I disorder of OCD, Eating disorder or any non-anxiety related Axis 1 diagnosis. 2. Subjects who meet DSM-IV criteria for substance dependence confirmed by the SCID, for any substance except nicotine, within 3 months of screening. 3. Subjects who meet DSM-IV criteria for substance abuse within 3 months of screening. 4. Subjects with positive urine toxicology screen for illicit substances of abuse (aside from cannabis, if patient not abusing and agrees to stop use). 5. Subjects with a history of clinically significant cardiac, renal, neurologic, cerebrovascular, metabolic, or pulmonary disease, or other disease or clinical findings that are unstable, or that in the opinion of the investigator, would confound biological assessments. 6. Female subjects who are pregnant or who are breastfeeding or planning to become pregnant during the study. 7. Subjects who, in investigator's opinion, would be non-compliant with the study procedures 8. Subjects with current psychotic symptoms (delusions or hallucinations). 9. Existing sleep problems unrelated to the depression 10. Potential study subjects who are actively suicidal Healthy Volunteers must fulfill all of the following inclusion criteria: 1. Able to provide informed consent before beginning any study-specific procedures 2. Not meet a current or lifetime DSM-IV Axis I disorder 2\) Male and female patients at least 18 years of age 3) Women with reproductive potential must have a negative pregnancy test; 4) Medication free, including herbal medications 5) Negative drug screen for drugs of abuse. 6) PSQI of \< 5 Healthy volunteers will be excluded if: 1. A current or lifetime DSM-IV Axis I disorder. 2. A positive urine toxicology screen for illicit substances of abuse (aside from cannabis, if not abusing and agrees to stop use). 3. A history of clinically significant cardiac, renal, neurologic, cerebrovascular, metabolic, or pulmonary disease, or other disease or clinical finding that is unstable or that, in the opinion of the investigator, would confound biological assessments. 4. Females who are pregnant, breastfeeding or planning to become pregnant during the study. 5. People who, in investigator's opinion, would be non-compliant with the study procedures.