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ultradian

 
(ŭl-trā'dē-ən) pronunciation
adj.
Relating to or exhibiting periodic physiological activity that occurs more than once every 24 hours.

[ULTRA- + (CIRCA)DIAN.]


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(ŭl-trā'dē-ən)
adj.

Relating to or exhibiting periodic physiological activity that occurs more than once every 24 hours.


(of a biological activity) occurring less often than once per 24-hour period. Compare circadian, infradian.

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Pertaining to a period of less than 24 hours; applied to the rhythmic repetition of certain phenomena in living organisms occurring in cycles of less than a day (ultradian rhythm).

Ultradian rhythms are recurrent periods or cycles repeated throughout a 24-hour circadian day. In contrast, infradian rhythms, such as the human menstrual cycle, have periods longer than a day.

The descriptive term ultradian is used in sleep research in reference to the 90–120 minute cycling of the sleep stages during human sleep.[1]

Some of the other ultradian cyclings of the body are 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, which 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.[2]

Notes

  • ^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.[2]

References

  1. ^ 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. http://www.nature.com/nrn/journal/v3/n9/full/nrn915.html. 
  2. ^ a b 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. 

 
 
Related topics:
biological rhythm
rhythm
Biological Rhythms

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