In sensor network applications, the major traffic pattern consists of data collected from several source nodes to a sink through a unidirectional tree. In this paper, the authors propose DMAC (Data Gathering Medium Access Control), an energy efficient and low latency for data gathering in WSNs (Wireless Sensor Networks). Previously MAC protocols that utilize activation/sleep duty cycles suffer from a data forwarding interruption problem, whereby not all nodes on a multihop path to the sink are notified of data delivery in progress, resulting in significant sleep delay. DMAC is proposed to solve the interruption problem and allows continuous packet forwarding by giving the sleep schedule of a node an offset that depends upon its depth on the tree. DMAC also adjusts the duty cycles adaptively according to the traffic load in the network. the authors further propose a data prediction mechanism and the use of More-To-Send (MTS) packets in order to alleviate problems pertaining to channel contention and collisions. the simulation results show that by exploiting the application specific structure of data gathering trees in sellsor networks, DMAC provides significant energy savings and latency reduction while ensuring high data reliability.