Energy efficiency of the MAC protocol is a key design for wireless sensor networks (WSNs). Due to the of the problem, a number of energy efficient protocols have been developedfor WSNs. Preamblesampling MAC protocols (e.g., B-MAC and X-MAC) overheads due to their preambles, and are inefficient large wakeup intervals. SCP-MAC, a very energy efficient MAC protocol, minimizes the preamble by preamble sampling and scheduling techniques;, it does not prevent energy loss due to overhearing;addition, due to its synchronization procedure, it results increased contention and delay. In this paper, we an energy efficient MAC protocol for WSNs that overhearing and reduces contention and delay by scheduling the wakeup time ofneighboring. To validate our design and analysis, we implement proposed scheme on the MicaZ platform. Experimental show that AS-MAC considerably reduces energy, packet loss and delay when compared with MAC.