As power efficiency is one of the most severe constraints in wireless sensor networks, we propose a scheduling protocol for reducing power dissipation. The protocol (DB-TDMA) is a hybrid of depth based scheduling and TDMA, which is applicable to clustering topology. Depth based scheduling is adopted for cluster heads scheduling, and TDMA is for member nodes scheduling in a cluster. DB-TDMA supports fluctuated demand in the network. It reduces the energy required for listening and receiving. Simulation results show that DB-TDMA outperforms two existing scheduling protocols both in schedule construction efficiency and schedule quality.