There are several types of bipolar and related disorders. They may include mania or hypomania and depression. Symptoms can cause unpredictable changes in mood and behavior, resulting in significant distress and difficulty in life. 
Bipolar I disorder. You've had at least one manic episode that may be preceded or followed by hypomanic or major depressive episodes. In some cases, mania may trigger a break from reality (psychosis).
Bipolar II disorder. You've had at least one major depressive episode and at least one hypomanic episode, but you've never had a manic episode.
Cyclothymic disorder. You've had at least two years — or one year in children and teenagers — of many periods of hypomania symptoms and periods of depressive symptoms (though less severe than major depression).
Other types. These include, for example, bipolar and related disorders induced by certain drugs or alcohol or due to a medical condition, such as Cushing's disease, multiple sclerosis or stroke.
 Bipolar II disorder is not a milder form of bipolar I disorder, but a separate diagnosis. While the manic episodes of bipolar I disorder can be severe and dangerous, individuals with bipolar II disorder can be depressed for longer periods, which can cause significant impairment. Although bipolar disorder can occur at any age, typically it's diagnosed in the teenage years or early 20s. Symptoms can vary from person to person, and symptoms may vary over time. Mania and hypomania Mania and hypomania are two distinct types of episodes, but they have the same symptoms. Mania is more severe than hypomania and causes more noticeable problems at work, school and social activities, as well as relationship difficulties. Mania may also trigger a break from reality (psychosis) and require hospitalization. Both a manic and a hypomanic episode include three or more of these symptoms: 
Abnormally upbeat, jumpy or wired
Increased activity, energy or agitation
Exaggerated sense of well-being and self-confidence (euphoria)
Decreased need for sleep
Unusual talkativeness
Racing thoughts
Distractibility
Poor decision-making — for example, going on buying sprees, taking sexual risks or making foolish investments
 Major depressive episode A major depressive episode includes symptoms that are severe enough to cause noticeable difficulty in day-to-day activities, such as work, school, social activities or relationships. An episode includes five or more of these symptoms: 
Depressed mood, such as feeling sad, empty, hopeless or tearful (in children and teens, depressed mood can appear as irritability)
Marked loss of interest or feeling no pleasure in all — or almost all — activities
Significant weight loss when not dieting, weight gain, or decrease or increase in appetite (in children, failure to gain weight as expected can be a sign of depression)
Either insomnia or sleeping too much
Either restlessness or slowed behavior
Fatigue or loss of energy
Feelings of worthlessness or excessive or inappropriate guilt
Decreased ability to think or concentrate, or indecisiveness
Thinking about, planning or attempting suicide
 Other features of bipolar disorder Signs and symptoms of bipolar I and bipolar II disorders may include other features, such as anxious distress, melancholy, psychosis or others. The timing of symptoms may include diagnostic labels such as mixed or rapid cycling. In addition, bipolar symptoms may occur during pregnancy or change with the seasons. Symptoms in children and teens Symptoms of bipolar disorder can be difficult to identify in children and teens. It's often hard to tell whether these are normal ups and downs, the results of stress or trauma, or signs of a mental health problem other than bipolar disorder. Children and teens may have distinct major depressive or manic or hypomanic episodes, but the pattern can vary from that of adults with bipolar disorder. And moods can rapidly shift during episodes. Some children may have periods without mood symptoms between episodes. The most prominent signs of bipolar disorder in children and teenagers may include severe mood swings that are different from their usual mood swings.