From biochemical oscillations to population dynamics, going through cell cycle and circadian clocks, cyclic behaviours are present at each and every scale of biological complexity. Their dynamics are inherent to biological processes ranging from metabolism and signalling to development and behaviour, leading to obvious and sometimes highly deleterious effects when they are malfunctioning. Nature cycles and recycles at every scale and understanding the mechanisms underlying these phenomena is of paramount importance if we want to have a global understanding of biological complexity.