The lifetime of wireless sensor networks can be increased by minimizing the number of active nodes that provide complete coverage, while switching off the rest. In this paper, we propose a distributed and scalable node-scheduling algorithm that conserves overall system energy by minimizing the number of active nodes, localizing the execution to the dying sensor(s), and minimizing the frequency of execution by reacting only to the occurrence of a sensing hole. This effects an increased system lifetime while maintaining coverage over an application-defined threshold value. We compare our algorithm to a network with a centralized node-scheduling algorithm. Our results show equivalent coverage degree over a wide range of sensor networks.