A network node (12, 17) dynamically configures and controls assistance information transmissions by wireless communications devices (14) in a wireless communications system (10). The assistance information facilitates performance of power saving adaptations for the wireless communications device (14). The network node (12, 17) configures what information to indicate in assistance information messages, how the message is sent by wireless communications devices (14), and/or when the message should be signaled. The wireless communications devices (14) transmit assistance information messages in accordance with configuration parameters signaled by the network node (12, 17).