In chronobiology, an infradian rhythm is a rhythm with a period longer than the period of a circadian rhythm, i.e., with a frequency of less than one cycle in 24 hours.[1] Some examples of infradian rhythms in mammals include menstruation, breeding, migration, hibernation, molting and fur or hair growth, and tidal or seasonal rhythms. In contrast, ultradian rhythms have periods shorter than the period of a circadian rhythm. Several infradian rhythms are known to be caused by hormone stimulation or exogenous factors. For example, seasonal depression, an example of an infradian rhythm occurring once a year, can be caused by the systematic lowering of light levels during the winter.[2]
The most well-known infradian rhythm in humans is the menstrual cycle.[3] The seasonal affective disorder, a rhythm occurring once a year, is also classified as infradian by some writers.[4][5]
Other writers more narrowly define infraradian rhythms as rhythms longer than 24 hour but shorter than one year; categorizing rhythms of about a year as circannual rhythms (circannual cycle).[6][7]
Some studies observe an infraradian rhythm with a period of approximately 7 days (circaseptan rhythm).[8][9] However, these rhythms appear to be an artifact of the statistics applied to the raw data.[10]
See also edit
References edit
- ^ Brown, Frederick M. & Graeber, R. Curtis, eds. The Rhythmic Aspects of Behavior. Hillsdale, NJ: Lawrence Erlbaum Associates. 1982, (p.462).
- ^ "Infradian and ultradian rhythms for A level psychology - Psychteacher". www.psychteacher.co.uk. Archived from the original on 2015-02-28.
- ^ Joe Boland. "Infradian Rhythm: Understanding Your Body’s Long Game". 2024.
- ^ Carrie Arnold. "What Is Infradian Rhythm, and How Does It Affect Sleep? ". 2022.
- ^ "Infradian Rhythms: What They Are and Why They Matter". 2022.
- ^ Gregory E. Demas and Lance J. Kriegsfeld. "Biological Rhythms". doi:10.1016/B0-12-475570-4/00196-7 2004.
- ^ "A brief history of circannual time". doi:10.1111/jne.12694 2019.
- ^ "Characteristics of infradian and circadian rhythms in the persistent vegetative state ". doi:10.1177/147323001103900625 2011.
- ^ "Ultradian and Infradian Rhythms in the Dynamic of Testosterone Concentration in the Serum of the White-Breasted Hedgehog Erinaceus roumanicus".
- ^ Fred W. Turek. "Circadian Rhythms". doi:10.1016/B978-0-12-571149-4.50007-6 1994.
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