Neurons in the suprachiasmatic nucleus (SCN) of the hypothalamus are thought to communicate time of day information through circadian (~24-hour) variation of their firing frequency, with low rates during the night and higher rates during the day. Based on a mathematical model of the ionic currents within SCN neurons, we predict that the neural code of the SCN is more complex and that throughout the day clock-containing SCN neurons can transition between firing and quiescent states, including an unusual depolarized rest state. We also simulate networks of SCN neurons at a set circadian phase with GABAergic coupling, and observe the formation of clusters of neurons with near synchronous firing. We find that the clustering depends on network properties such as synaptic strength and density. Experimental data supporting these modeling results will be discussed.