Ultradian rhythm

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An ultradian rhythm is a recurrent period or cycle repeated throughout a 24-hour circadian day. In contrast, infradian rhythms, such as the human menstrual cycle, have periods longer than a day. The Oxford English Dictionary's definition of Ultradian specifies that it refers to cycles with a period shorter than a day but longer than an hour.[1]

The descriptive term ultradian is used in sleep research in reference to the 90–120 minute cycling of the sleep stages during human sleep.[2]

There is a circasemidian rhythm in body temperature and cognitive function which is technically ultradian. However, this appears to be the first harmonic of the circadian rhythm of each and not an endogenous rhythm with its own rhythm generator.

Other ultradian rhythms include blood circulation, blinking, pulse, hormonal secretions such as growth hormone,[3] heart rate, thermoregulation, micturition, bowel activity, nostril dilation, appetite, and arousal. Ultradian rhythms of appetite require antiphasic release of Neuropeptide Y (NPY) and Corticotropin-releasing hormone (CRH), stimulating and inhibiting appetite ultradian rhythms.[4] Recently, ultradian rhythms of arousal lasting approximately 4 hours were attributed to the dopaminergic system in mammals.[5] When the dopaminergic system is perturbed either by use of drugs or by genetic disruption, these 4 hours rhythms can lengthen significantly into the infradian (>24hr) range, sometimes even lasting for days (>110hr) when methamphetamines are provided.[citation needed]

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. Ultradian mood cycling is characterized by cycles shorter than 24 hours.[6]


  1. ^ "Ultradian, adj.". Oxford English Dictionary. Retrieved 18 February 2014.  available online to subcribers, also in print
  2. ^ 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/nrn915. PMID 12209117. 
  3. ^ Tannenbaum, Gloria S. (1976). "Evidence for an endogenous ultradian rhythm governing growth hormone secretion in the rat". Endocrinology. 98 (3): 562–570. doi:10.1210/endo-98-3-562. 
  4. ^ Kalra, S.P.; Kalra, P.S. (2004). "NPY and cohorts in regulating appetite, obesity and metabolic syndrome: beneficial effects of gene therapy.". Neuropeptides. 38 (4): 201–211. doi:10.1016/j.npep.2004.06.003. 
  5. ^ Blum, I.D.; Zhu, L.; Moquin, L.; Kokoeva, M.V.; Gratton, A.; Giros, B.; Storch, K.F. (2014). "A highly tunable dopaminergic oscillator generates ultradian rhythms of behavioral arousal.". eLife. 3. doi:10.7554/eLife.05105. PMC 4337656free to read. PMID 25546305. 
  6. ^ 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.