Sleep is thought to mediate both mnemonic and homeostatic functions. However, the mechanism by which this brain state can implement both the "selective" plasticity needed to consolidate novel memory traces as well as the "general" plasticity necessary to maintain a well-functioning neuronal system is unclear. Recent findings show that both of these functions differentially affect neurons based on their intrinsic firing rate, a ubiquitous neuronal heterogeneity. Furthermore, they are both implemented by the NREM slow oscillation, which also distinguishes neurons based on firing rate during sequential activity at the DOWN->UP transition. Together, these results suggest a mechanism by which the slow oscillation enacts homeostatic maintenance of the neuronal firing rate distribution, and "perturbation" of that activity by hippocampal replay acts to integrate new memory traces into the existing cortical network.