Fig. 1: Two potential bifurcations underlying the loss of rhythmicity at low temperatures.
From: Low temperature abolishes human cellular circadian rhythm through Hopf bifurcation
The loss of self-sustained circadian rhythms under low temperatures can be explained by two mathematical scenarios. Around the critical temperature, the oscillator behaves differently under the different bifurcations. In Hopf bifurcation, the oscillation amplitude decreases to zero while the period remains relatively stable. In addition, the self-sustained oscillator turns into a damped oscillator at the critical point. Meanwhile, in SNIC bifurcation, the oscillation period extends and eventually diverges to infinity. The self-sustained oscillation can be transformed into an excitable system at the bifurcation point.
