Internal noise stochastic resonance in a circadian clock system

We have studied the influence of internal noise on a circadian clock system using stochastic simulation methods and chemical Langevin equations. It is found that internal noise can induce circadian oscillations, when the corresponding deterministic system does not oscillate. The performance of the noise induced circadian oscillation undergoes a maximum with the variation of the internal noise level, showing the occurrence of internal noise stochastic resonance. Since the magnitude of the internal noise is changed via the variation of the system size, these phenomena also demonstrate a kind of system size resonance.