The authors propose a new power saving scheme based on a buffer-threshold and timer in wireless packet networks. In a standard sleep mode operation with a binary exponential algorithm, a mobile station (MS) can begin a wake period if it is aware of the existence of its own downlink packets during a listening interval. In a light traffic environment, this conventional standard operation consumes a considerable amount of power to switch modes (sleep/listen/wake). To solve this problem, a new power saving scheme based on joint control of buffer-threshold and timer (JCBT) is proposed. To see the performance behaviour of the JCBT scheme, the authors consider the total power consumption per unit time and the average packet transfer delay as performance measures. Based on the performance measures, the authors obtain the optimal solution for the proposed JCBT scheme that minimises the total power consumption per unit time with a given delay requirement.