This application provides a communication method and a related apparatus. The method is applied to a first terminal device, and the first terminal device is a terminal device that uses sidelink discontinuous reception SL DRX. The method includes: sending a first message to a second terminal device, where the first message includes a first resource set, and the first resource set is used by the second terminal device for SL transmission; and using a resource corresponding to the first resource set as activation time of the SL DRX, or disabling the SL DRX on the resource corresponding to the first resource set; and monitoring sidelink control information SCI on the resource corresponding to the first resource set, where the SCI includes SCI from the second terminal device. Embodiments of this application are implemented to avoid impact on quality of communication between terminal devices.