<prompt> In mood disorder, rapid cyclers are defined as4 or more episodes per yearMania occuring during summerMania consistent during lunar yearDepressive episodes during winter  <response>: A 4 or more episodes per year Rapid cycling: Most people who meet criteria for bipolar disorder experience a number of episodes, on average 0.4 to 0.7 per year, lasting three to six months. Rapid cycling, however, is a course specifier that may be applied to any of the above subtypes. It is defined as having four or more episodes per year and is found in a significant fraction of individuals with bipolar disorder. The definition of rapid cycling most frequently cited in the literature including the DSM is that of Dunner and Fieve: at least four major depressive, manic, hypomanic or mixed episodes are required to have occurred during a 12-month period.There are references that describe very rapid ultra-rapid or extremely rapid ultra-ultra or ultradian cycling. One definition of ultra-ultra rapid cycling is defining distinct shifts in mood within a 24-48-hour period. 