Abstract— This letter proposes energy saving medium access control (MAC) protocol (NSL-MAC) for data gathering in the wireless sensor network (WSN) by using unmanned aerial vehicle (UAV). The primary goal is to enhance the network performance and prolong the lifetime of nodes. The UAV is used as a mobile sink node to gather the data from the nodes. In NSL-MAC, the active duration of a node can be maintained dynamically. The node only active when it is inside of the communication range of the UAV. Furthermore, the registered node only active during their transmission schedule which has been assigned in the scheduling period. On the other hand, the unregistered nodes contend to send the registration frame to the UAV during the registration period. Simulation results verify that NSL-MAC enhances the network performance and brings energy efficiency to the nodes.