Hypomania (literally, below mania) is a mood state characterized by persistent and pervasive elated or irritable mood, and thoughts and behaviors that are consistent with such a mood state. It is distinguished from mania by the absence of psychotic symptoms and by its lower degree of impact on functioning. Hypomania is a feature of some mood disorders, such as bipolar II disorder and cyclothymia. Though hypomanic people are often associated with bipolar disorder, it is in this state that many creative talents are in their most productive and successful mood. Ideas come to one with hypomania easily, and there is a full awareness of what they are doing, unlike intense forms of mania.

Source: http://en.wikipedia.org/wiki/Hypomania