infradian
/ɪnˈfreɪdɪən
/adjective Physiology
(Of a rhythm or cycle) having a period of recurrence longer than a day; occurring less than once a day. Compare with ultradian.The crayfish Procambarus clarkii is a nocturnal organism that displays a span of overt circadian and infradian rhythms to adapt to daily and seasonal environmental lighting changes....
- The circadian rhythm resides with an infradian rhythm of lunar 28-day cycles, seasonal cycles of cold and hot as well as shifting light and dark.
- In this paper, a presumptive role for infradian hormonal rhythms is considered.
Origin
Mid 20th century: from infra- 'below' (i.e. expressing a lower frequency), on the pattern of circadian.