Disclosed is a method and system to reduce user equipment (UE) battery consumption and efficiently utilize uplink hybrid automatic repeat request (HARQ) memory, including sending uplink data to a base station and saving a backup copy of the uplink data in an uplink HARQ buffer, receiving an acknowledgement from the base station indicating that the uplink data has been received, measuring a HARQ retransmission time required to retransmit the uplink data to the base station after receiving the acknowledgement, comparing the measured HARQ retransmission time to a remaining discontinuous reception cycle, and removing the uplink data from the uplink HARQ buffer after expiration of an inactivity timer and switching the UE to a sleep mode based on the comparison.