Infradian rhythm

From Wikipedia, the free encyclopedia

An infradian rhythm is a rhythm with a period greater than the period of a circadian rhythm, i.e. with a frequency smaller than one cycle in 28 hours.^[1] In contrast, ultradian refers to rhythms with periods smaller than the period of a circadian rhythm.

[edit] Infradian rhythms in menstruation

The human menstrual cycle is an example of an infradian rhythm, the timing of which is governed by both endogenous (internal) biological cycles and exogenous cues (zeitgebers).

One exogenous cue is pheromone production, which can bring menstrual cycles into synchronization with those of other women where they are in close proximity for an extended period of time. Russell et al. applied the pheromones of one woman to a group of sexually inactive women. A swab was taken from the donors armpits daily, and this was rubbed on to the upper lip of the women (after having removed the bacteria). It was found that 4/5 of the women synchronized with the donor woman.^{[citation needed]}

[edit] References