MAC layer protocols play important role in wireless sensor networks to save energy and increase the lifetime of battery. In recent years, many MAC protocols are proposed to minimize the energy requirements. In this paper, we propose an adaptive WiseMAC protocol to further enhance the energy efficiency of wireless sensor networks as well as for variable traffic conditions. Proposed protocol incorporates dynamic duty cycle as well as adaptive contention window schemes. We have simulated the protocol in NS2 environment and checked the performance. It demonstrates that the proposed protocol is capable of providing higher energy efficiency for the low throughput applications in comparison to other existing sensor MAC protocols. © 2016 IEEE.