Instabilities in breathing pattern are a common feature of sleep, giving rise to a variety of syndromes that vary in the magnitude of respiratory disturbance but that all lead to frequent arousals and sleep fragmentation. Although these syndromes vary in intensity of respiratory disturbance, the underlying mechanism of each is determined to a large extent on the neural processes that promote periodicities in net respiratory output. This review focuses on recent publications that have evaluated central brainstem processes for their involvement in the initiation and resolution of an apneic episode. In particular, this review focuses on several neural processes that can play an important role in promoting respiratory instability. These include spontaneous oscillations within the respiratory network, instability in the chemical control system due to increased gain in the feedback controller, differences in the controller gains of the upper airway and pump muscle effectors, state-dependent instabilities, and loss of stabilizing processes (eg, poststimulus potentiation.)