This paper presents SSP (Sleep Scheduling Protocol), a centralized scheme for extending the lifetime of densely deployed wireless sensor networks by keeping only a necessary set of sensor nodes active. We present an algo­rithm for finding out which nodes should be put into sleep mode, and the algorithm preserves coverage and connectiv­ity while trying to put as much nodes as possible into sleep mode. The algorithm is executed at the base station period­ically. In this way, the network is reconfigured periodically, which also helps to a more even distribution of energy con­sumption load to sensor nodes. We evaluated our proto­col via simulations and observed a significant increase in the lifetime, depending on the node density, while providing good coverage.