Which method is an effective way to minimize proactive and retroactive interference? decreasing sleep time making the material meaningful scheduling back-to-back study times for topics that are similar studying before sleeping?

I believe the answer is: studying before sleeping

Retroactive interference refers to a process when newer information prevent older information from being recalled. Proactive interference refers to the situation when Old information prevent new information from being recalled. Studying before sleeping can reduce the amount of this interference and make new information become more likely to be stored in the memory without any disturbance.