It is called manic depression and it is true illness. 
manic depression, is a 
mental disorder that causes periods of 
depression and periods of elevated 
mood.The elevated mood is significant and is known as 
mania or 
hypomania, depending on its severity, or whether symptoms of 
psychosis are present. During mania, an individual 
behaves or feels 
abnormally energetic, happy, or irritable.
Mania is a distinct period of at least one week of elevated or irritable 
mood, which can range from euphoria to delirium, and those experiencing hypo- or mania may exhibit three or more of the following behaviors: 
speak in a rapid, uninterruptible manner, short 
attention span, 
racing thoughts, increased 
goal-oriented activities, agitation, or they may exhibit behaviors characterized as impulsive or high-risk, such as 
hypersexuality or excessive spending.To meet the definition for a manic episode, these behaviors must impair the individual's ability to socialize or work.If untreated, a manic episode usually lasts three to six months.