Bipolar disorder is a serious mental illness that affects over 2% of the US population. It is characterized by dramatic mood swings and there are five distinct types: (1) Bipolar 1 Disorder involves periods of mania and depression without a set duration; (2) Bipolar 2 Disorder includes less severe hypomania and depression; (3) Cyclothymia Disorder has shorter periods of hypomania and depression; (4) Mixed Features involves concurrent depression and mania or excess energy with sleep issues; (5) Rapid-Cycling involves manic and depressive episodes lasting days or hours. The document provides an overview of the symptoms of each type of bipolar disorder.