Those with bipolar disorder experience both low, depressive episodes as well as high, energetic manic episodes. Both types of episodes may be extremely detrimental to daily functioning. When beset by a major depressive episode, a sufferer may find it difficult to get out of bed in the morning, yet when experiencing mania, he may be in a euphoric state with a false senses of happiness. There are two categories of bipolar disorders: bipolar I and bipolar II. Bipolar I disorder is characterized by recurring episodes of full mania and severe depression, while those with bipolar II disorder experience mild symptoms of mania (hypomania) alternating with major depressive episodes.  In cases of cyclothymia, a person will have mild depression alternating with hypomania for at least two years.  Sufferers of bipolar disorder generally have very unstable emotions and interpersonal issues due to the inconsistency of their moods. Approximately 1.0-2.6% of adults in the world at a given time have bipolar disorder.