Medium Access Control (MAC) protocol consists of sets of rules that determine which node is allowed to access the transmission medium. It provides mechanism for collision avoidance such that interfering sensor nodes do not transmit at the same time. In the literature, researchers have proposed different MAC protocols with features aimed at improving energy efficiency and thereby prolonging the life of sensor nodes. Sensor MAC, Time-out MAC (T-MAC), Dynamic Sensor MAC (DSMAC), WiseMAC, Quorum-based MAC (Queen-MAC) and Traffic Adaptive Medium Access Protocol (TRAMA) are some examples of proposed MAC protocols. There is a duration field in each transmitted packet. The value of this field indicates how long it will take to complete the remaining packet transmission. In the current paper, a novel energy-efficient MAC protocol is proposed based on the use of duration value in transmitted packets to setup varying sleep/wake-up schedules for neighbouring nodes of the receiver. The effectiveness of this proposed Packet-Duration-Value-based MAC (PDV-MAC) protocol is tested via Simulation which is implemented in Visual C# and MATLAB. It is shown by the results obtained that the proposed MAC protocol can indeed be implemented in sensor nodes to improve energy efficiency in wireless sensor network.