A method and a user equipment (UE) for controlling Discontinuous Reception (DRX) behavior on multiple radio interfaces are provided. The method includes receiving, from a Base Station (BS), a first set of timers configured for controlling a first DRX behavior of the UE on a Uu interface to the BS; performing control channel monitoring according to the first set of timers; identifying that a Sidelink (SL) activity occurs on an SL interface that is a PC5 interface, the SL activity associated with one or more SL destinations on the PC5 interface; and starting or restarting at least one of the first set of timers in response to identifying the SL activity.