In recent years, wireless sensor networks (WSNs) have a rapid development and they take a lot of research attention because of their wide-range applications. A WSN consists of a large number of distributed sensor nodes. These nodes are often deployed in remote or hostile areas to monitor physical or environmental conditions where they send this data to a main location. The most critical parameter in WSNs is network lifetime, so an efficient routing protocol is essential to reduce the energy consumption and to increase the network lifetime. This paper proposes an energy-efficient chain-based cooperative routing protocol based on node sleep/wake-up mechanism for WSNs. We compare this protocol with two efficient protocols; LEACH and CBCCP using MATLAB. Simulation results show that the proposed algorithm achieves better performance and conserves more energy than the other two protocols.