|Look up ultradian in Wiktionary, the free dictionary.|
Some of the other ultradian cyclings of the body are blood circulation, blinking, pulse, hormonal release, heart rate, thermoregulation, urination, bowel activity, nostril dilation and appetite. The last involves rhythmic release of Neuropeptide Y (NPY) and Corticotropin-releasing hormone (CRH), stimulating and inhibiting appetite ultradian rhythms.
Caenorhabditis elegans is often used as a model animal for ultradian rhythm. Defecation in C. elegans is a tightly controlled rhythmic process. Posterior body wall muscle contractions in C. elegans occur rhythmically every 45–50 seconds and mediate defecation.
Ultradian mood states in bipolar disorder cycle much faster than rapid cycling; the latter is defined as four or more mood episodes in one year, sometimes occurring within a few weeks.a Ultradian mood cycling is characterized by cycles shorter than 24 hours.
- ^a The term rapid cycling was defined prior to discovery of ultradian mood states. Thus it can be misleading to think of these states as ultra-rapid cycling, as this particular form of cycling is also described as a mixed state, and has not gained universal acceptance. Both terms are unable to capture the nature of this unique form of manic-depressive illness.
- Hobson JA, Pace-Schott EF (September 2002). "The cognitive neuroscience of sleep: neuronal systems, consciousness and learning". Nat. Rev. Neurosci. 3 (9): 679–93. doi:10.1038/nrn91510.1038/nrn915. PMID 12209117.
- Kramlinger KG, Post RM (March 1996). "Ultra-rapid and ultradian cycling in bipolar affective illness". Br J Psychiatry 168 (3): 314–23. doi:10.1192/bjp.168.3.314. PMID 8833685.