5. At point of enrollment, diagnosis of major depression, bipolar disorder, seasonal affective disorder, or anxiety disorder for which the patient is currently taking any of the following medications: selective serotonin reuptake inhibitors (SSRIs), Tricyclic antidepressants, monoamine oxidase inhibitors, lithium, benzodiazepines, barbiturates, drugs acting on the 5-HT receptors. Patients meeting these criteria may still enroll in the study if they are on a chronic, stable, low-dose regimen for at least 3 months prior to enrollment, as determined by the on-site PIs and co-investigating physicians. Patients having to begin on a regimen of any of these medications while on the study may continue on the study.