The collective term bipolar covers several different types of bipolar disorder categorised by the duration, extent and/or frequency of symptoms.^2,3,5,6

• Bipolar I disorder – the person has experienced at least one episode of mania that has lasted at least seven days (but usually much longer), usually with periods of deep depression, although some people will only experience manic episodes. If left untreated, manic episodes typically last 3-6 months, and depressive episodes last 6-12 months.
• Bipolar II disorder – there has been at least one period of major depression, but periods of elevated mood are at the hypomania level, rather than mania, and lasting four days or more.
• Bipolar disorder with mixed features – periods of mania/hypomania can occur at the same time as depression.
• Bipolar disorder with seasonal pattern – the depression and/or mania can appear to fluctuate with the changing seasons, although the opposite mood may not necessarily be seasonal.
• Rapid cycling – four or more mood episodes happening in a 12-month period (whether bipolar I or II)
• Cyclothymia – depression and hypomania episodes occurring regularly for at least 2 years, but symptoms are less severe than bipolar disorder but may last longer and may progress to bipolar disorder.