Complex sentence: Bipolar disorder (also known as bipolar affective disorder, manic-depressive disorder, or manic depression) is a mental illness characterized by episodes of an elevated or agitated mood known as mania often alternating with episodes of depression.
Split into simpler sentences: Bipolar disorder (also known as bipolar affective disorder, manic-depressive disorder, or manic depression) is a mental illness. Individuals with bipolar disorder experience episodes of an elevated or agitated mood known as mania, alternating with episodes of depression.