Recent few years are proved very progressive in terms of energy efficient protocols in Wireless Sensor Networks, but energy efficiency is still a point of focus in sensor networks. Among various MAC layer protocols, WiseMAC is known as one of the most energy efficient protocols. Non-Persistent Carrier Sense Multiple Access (NP-CSMA) and the preamble sampling are the main techniques used in basic WiseMAC protocol. Basically they are used to reduce the power consumption when energy is wasted in listening to idle medium. This paper investigates the WiseMAC protocol with different important schemes that are used in implementation of WiseMAC in sensor networks. These schemes basically emphasize on energy saving methods in WiseMAC. Various modifications are done to the original WiseMAC to make it more energy efficient; with the same motive of increasing energy efficiency, adaptive WiseMAC protocol with dynamic duty cycle and the adaptive Contention Window is proposed. © 2013 IEEE.