Ambient Intelligence is one of the research area where wireless sensor devices are commonly used. Main idea of these applications is to monitor and recognize people's indoor or outdoor activities. In this study, we focus on one of the major problem of WSN which is energy consumption in a different way from the existing approaches in the literature. With the proposed approach, it is shown that it is possible to create a dynamic sleep scheduling mechanism for each recognized activity. In contrast to previous studies found in the literature review, in our perspective, a holistic approach which takes component and application level into account is proposed, therefore energy consumption and the ways for improving lifetime of node and the network are handled. Main aim is to find a suitable region where application can work with tolerable performance degradation meanwhile lifetime of the sensor is extended by decreasing energy consumption. Proposed approach is tested on accelerometer signal of walking activity. It is shown that it exists a region where application performance and energy gain are suitable.