Dynamics of the two process model of human sleep regulation

We examine the dynamics of the two process model of human sleep regulation. In this model, sleep propensity is governed by the interaction between a periodic threshold (process C) and a saturating growth/decay (process S). We find that the parameter space of this model admits sleep cycles with a wide variety of characteristics, many of which are not observed in normal human sleepers. We also examine the effects of phase dependent feedback on this model.