We propose a distributed and efficient sleeping protocol, the energy-balanced coordinated node scheduling (ECONS), that guarantees OoS sensing coverage for wireless dense sensor networks. We first define the parameters that can be adjusted by the applications to achieve the desired sensing coverage percentage. We next discusses the ECONS protocol which maximizes the network lifetime while supporting the QoS coverage requirements. The key components include accurate sleeping eligibility calculation, proper back-off schemes, overhead cost control, and dynamic off-duty interval assignment that adapts to the energy consumption patterns of sensors in each neighbors. Simulations using realistic network application scenario and energy models based on MICA2 measurements confirm the efficiency of ECONS, which achieves an increase of 49% to 71.5% in network lifetime compared to non-scheduled networks and 18.9% compared to coverage preserving (CP) protocol.