A distinct period during which the predominant mood of the sufferer is either elevated, expansive or irritable, of sufficient severity to cause marked impairment in occupational functioning or in usual social activities or relationships with others, or to require hospitalization to prevent harm to self or others. Associated symptoms include inflated self-esteem or grandiosity (which may be delusional, e.g. a special relationship to God), decreased need for sleep, pressure of speech, flight of ideas, distractibility, increased involvement in goal-directed activity, psychomotor agitation, and excessive involvement in pleasurable activities which have a high potential for painful consequences that the person often does not recognize. Almost invariably there is increased sociability. The activities have a disorganized, flamboyant, or bizarre quality. Frequently expansiveness, unwarranted optimism, grandiosity, and lack of judgement lead to such activities as buying sprees, reckless driving, foolish business investments, and sexual behaviour usual for the person. Manic episodes typically begin suddenly and last from a few days to months.