An atypical antidepressant medication that derives some of its effect from blocking the reuptake of serotonin, a brain neurotransmit-ter important to mood and emotion, and has other mechanisms that are not completely understood. It causes drowsiness, therefore it is usually given at night and is particularly effective in people with insomnia or other disturbances of sleep (used even as a chronic sleep aid in people without depression). Trazodone (Desyrel) also can cause HEADACHE, ORTHOSTATIC HYPOTENSION (a drop in blood pressure with a change in position), heart arrhythmias, and sexual dysfunctions including priapism (extended erection), ejaculation dysfunction, erectile dysfunction, and inability to reach orgasm. Because these side effects are fairly common, this is a medication to consider when other antidepressant medications are inappropriate. Tra-zodone generally does not have interactions with anti-parkinson’s medications, however.