Infradian Rhythms: These occur less frequently than once a day.

In contrast, infradian rhythms, such as the human menstrual cycle, have periods longer than a day.

Infradian rhythms, which are cycles longer than a day, such as the annual migration or reproduction cycles found in certain animals or the human menstrual cycle.

An infradian rhythm is a rhythm with a period longer than the period of a circadian rhythm, i.e. with a frequency less than one cycle in 28 hours, such as menstruation, breeding, tidal or seasonal rhythms.

Dr Roxana S. Dronca et al. from the Mayo Clinic found that the immune cycle is also evident in fluctuations beyond C-reactive protein, as it can be seen in "infradian immune biorhythms of both immune cell subpopulations and cytokines."