Infradian rhythm explained

In chronobiology, an infradian rhythm is a rhythm with a period longer than the period of a circadian rhythm, i.e., one cycle is longer than 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 (<24 hours) than the period of a circadian rhythm. Several infradian rhythms are known to be caused by hormone or neurotransmitter stimulation or by environmental factors such as the lunar cycles. 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 seasonal affective disorder can be classified as infradian, or as circannual, which means occurring on a yearly basis.^{[3] [4]}

The most well-known infradian rhythm in humans is the fluctuation of estrogens and progesterone across the menstrual cycle.^[5] Another example in humans is the ~10-day rhythms of enamel growth.^{[6] [7]} Other infradian rhythms have been documented in organisms such as dormice, lemmings, voles, lynx, mice, etc.

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).^{[8] [9]}

Some studies observe an infraradian rhythm with a period of approximately 7 days (circaseptan rhythm).^{[10] [11]} However, these rhythms appear to be an artifact of the statistics applied to the raw data.^[12]

See also

• Photoperiodicity

Notes and References

1. Brown, Frederick M. & Graeber, R. Curtis, eds. The Rhythmic Aspects of Behavior. Hillsdale, NJ: Lawrence Erlbaum Associates. 1982, (p.462).
2. Web site: Infradian and ultradian rhythms for A level psychology . www.psychteacher.co.uk . dead . https://web.archive.org/web/20150228085733/http://www.psychteacher.co.uk/biologicalrhythms/infradian_ultradian_rhythms.html . 2015-02-28.
3. Carrie Arnold. "What Is Infradian Rhythm, and How Does It Affect Sleep? ". 2022.
4. https://health.clevelandclinic.org/infradian-rhythm "Infradian Rhythms: What They Are and Why They Matter"
5. Joe Boland."Infradian Rhythm: Understanding Your Body’s Long Game".2024.
6. Mahoney . Patrick . February 2017 . Enamel biorhythms of humans and great apes: the Havers-Halberg Oscillation hypothesis reconsidered . Journal of Anatomy . 230 . 2. 272–281 . 10.1111/joa.12551 . 27726135 . 5244461 .
7. Risnes . S. . 1998 . Growth tracks in dental enamel . Journal of Human Evolution . 35 . 4–5 . 331–350 . 10.1006/jhev.1998.0229 . 0047-2484 . 9774498. 1998JHumE..35..331R .
8. Encyclopedia: Biological Rhythms . Encyclopedia of Endocrine Diseases . Elsevier . Demas . Gregory E. . 2004 . 345–351 . en . 10.1016/b0-12-475570-4/00196-7 . 978-0-12-475570-3 . Kriegsfeld . Lance J..
9. A brief history of circannual time . 30739343 . 2019 . Lincoln . G. . Journal of Neuroendocrinology . 31 . 3 . e12694 . 10.1111/jne.12694 .
10. Guan . J. . You . C. . Liu . Y. . Liu . Y. . Zhang . R. . Wang . Z. . 2011 . Characteristics of infradian and circadian rhythms in the persistent vegetative state . The Journal of International Medical Research . 39 . 6 . 2281–2287 . 10.1177/147323001103900625 . 1473-2300 . 22289544.
11. Rutovskaya . Marina . V . Kosyreva . Anna M. . Diatroptov . Mikhail E. . 2020 . Ultradian and Infradian Rhythms in the Dynamic of Testosterone Concentration in the Serum of the White-Breasted Hedgehog Erinaceus roumanicus . Scientific Reports . en . 10 . 1 . 6334 . 10.1038/s41598-020-63399-5 . 32286463 . 7156455 . 2020NatSR..10.6334R . 2045-2322.
12. Book: https://www.sciencedirect.com/science/article/abs/pii/B9780125711494500076 . 10.1016/B978-0-12-571149-4.50007-6 . Circadian Rhythms . Proceedings of the 1992 Laurentian Hormone Conference . 1994 . Turek . Fred W. . Recent Progress in Hormone Research . 49 . 43–90 . 8146437 . 978-0-12-571149-4 .