To reduce idle-time energy consumption, nodes in ad hoc networks can switch to a power-save mode. However, since operating all nodes in power-save mode limits network capacity, some nodes may need to stay in active mode to support forwarding. The main challenge of selecting nodes to stay in active mode stems from the need to conserve energy while maintaining communication. Although topology management protocols build a forwarding backbone of active nodes by powering down redundant nodes, such protocols incur proactive backbone maintenance overhead. The reactive approach, on-demand power management, manages node transitions from active to power-save mode based on routing information. However, node transitions are only traffic-driven and may result in keeping redundant nodes awake. To this end, we propose TITAN, which builds a backbone reactively using information about both ongoing communication and the current power-management mode of nodes. The design of TITAN is based on the trade-offs between waking up power-saving nodes on shorter routes and using longer routes that contain active nodes. Simulation results show that TITAN conserves energy while maintaining efficient communication without additional control overhead for topology management.