The last few years have seen a wide adoption of the IEEE 802.15.4 MAC/PHY standard for low-power communication between wireless sensor nodes. Within this work we study some fundamental drawbacks of the 802.15.4 specifications for multihop network deployments, which adversely affect efficient node energy consumption. These issues are rectified by investigating a timezone-based scheduling, V-Route, that builds on 802.15.4 beaconless mode to enable both a synchronized sleep scheduling and a bidirectional communication between nodes in the sensor network and the PAN coordinator. The contributions of V-Route are threefold: (1) mitigate collisions, (2) enable packet routing and (3) provide energy saving in a multihop context, while maintaining the full compliancy with the 802.15.4 standard. We present a performance evaluation on energy consumption and latency with real experiments on Philips AquisGrain sensor nodes. Enhancing 802.15.4-based multi-hop networks with V-Route yields energy reduction ranging from 27.3% to 85.3%.