The significant growth in the number of access points deployed in WLAN stimulates research efforts to focus on finding solutions to reduce the power consumed by their components. One promising approach is to put the access points (or at least its radio interface) into sleep mode when no activity is detected on the channel. In this paper we designed and implemented a measurement platform which can automatically send repeated sleep/wake up request to an access point, and measure the energy it consumes in each state. We define and conduct several experiments to evaluate four different techniques to control and manage the sleep/wake up procedure of an access point. We compare their performance in terms of the time needed to complete the wake up, the energy consumed, and the changes, if any, needed in the mobile terminals.