In this article, we propose a routing mechanism based on the RPL protocol in a wireless network that is equipped with a mix of short-range and long-range radios. We introduce Life-OF, an objective function for RPL which uses a combination of metrics and the diverse physical layers to boost the network's lifetime. We evaluate the performance of Life-OF compared to the classical MRHOF objective function in simulations. Two key performance indicators (KPIs) are reported: network lifetime and network latency. Results demonstrate that MRHOF tends to converge to a pure long-range network, leading to short network lifetime. However, Life-OF improves network lifetime by continuously adapting the routing topology to favor routing over nodes with longest remaining lifetime. Life-OF combines diverse radios and balances power consumption in the network. This way, nodes switch between using their short-range radio to improve their own battery lifetime and using their long-range radio to avoid routers that are close to depletion. Results show that using Life-OF improves the lifetime of the network by up to 470% that of MRHOF, while maintaining similar latency.