Depression is a mental illness affecting more than 350 million people worldwide. This condition is caused by unbalanced levels of naturally occurring chemicals in the brain and may lead to feelings of guilt, severe anxiety, irritability, or hopelessness. Patients suffering from this illness are encouraged to remember that it can be treated with medication and therapy just like other chronic health conditions. Antidepressants operate by rebalancing these levels of chemicals in the brain to reduce symptoms associated with this condition and to restore energy, interest in everyday activities, and sense of well-being.