The effect of noise and heterogeneity is studied in a multi-neuron generalization of a two-neuron model of wake-sleep cycle introduced recently [S. Postnova, K. Voigt, H.A. Braun, J. Biol. Rhythms 24, 523 (2009)]. This minimal but physiologically plausible two-neuron model introduced a mechanism of homeostatic regulation of sleep based on Orexin/Hypocretin, a co-transmitter of the lateral hypothalamus, and on Glutamate. It is shown that in the presence of an external periodic signal, representing e.g. a daily light stimulus or a circadian cycle, there are suitable levels of heterogeneity of the neuronal couplings or of the noise currents that are optimal for the system response to the external stimulus.