A mood illness called bipolar disorder, formerly known as manic depression, is characterized by cycles of melancholy and excessively heightened happiness that can last anywhere from days to weeks at a time.
Mania is the name for an elevated mood that is extreme or linked to psychosis; hypomania is the name for one that is less severe. Mania is a condition in which a person exhibits abnormally euphoric, cheerful, or irritated behavior or feelings and frequently acts impulsively without carefully considering the implications. During manic episodes, the need for sleep is typically decreased.