from Wiktionary, Creative Commons Attribution/Share-Alike License.

  • adjective Cyclical with a periodicity significantly longer than 24 hours, that is, less frequent than circadian.


Sorry, no etymologies found.


  • For longer naps, test multiples of 90 minutes, which is called an "ultradian" rhythm in some papers, though the proper term should be "infradian" since it's less than 24 hours.

    Tim Ferriss: Relax Like a Pro: 5 Steps to Hacking Your Sleep

  • This natural phenomenon has only recently become known to Western physicians, who call it ‘infradian rhythm,’ but Taoists have been aware of it for millennia.

    The Tao of Health, Sex and Longevity

  • The behavioral abnormalities include a severe working memory deficit and an exaggerated infradian rhythm, which are similar to symptoms seen in schizophrenia, bipolar mood disorder and other psychiatric disorders.

    BioMed Central - Latest articles

  • Among their findings, mice heterozygous for a null mutation of the alpha-isoform of calcium / calmodulin-dependent protein kinase II show profoundly dysregulated behaviors, including a severe working memory deficit and an exaggerated infradian rhythm (cycle of increases and decreases in locomotor activity in their home cage; 2-3 weeks / cycle), which are comparable to the symptoms observed in patients with schizophrenia, bipolar disorder and other psychiatric disorders. News Feed


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