Abstract
For studying autonomous circadian rhythms of proteins in organisms, various mathematical models have been proposed. In this study, we have investigated bifurcations of periodic oscillations observed in circadian models incorporating the effect on a light-dark cycle and show that the waveform of the periodic variation in the light-induced parameter has a marked influence on the global bifurcation structure or the type of dynamic behavior resulting from the forcing term of the circadian oscillator by the LD cycles