Medication has helped. I don't find myself in a room, not sure what I'm in there for, nearly as often. But it still happens lol.

It sounds simple, but make sure you're getting enough good quality sleep. I have delayed sleep phase disorder, which often occurs along with ADHD. My body is extra sensitive to blue light and the effect it has on circadian rhythm.

What helped me most was getting some red LED light strings, so I didn't have to turn any normal lights on at night. And using night mode/twilight/flux on my phone and computer. I don't really go to bed any earlier, but I wake up easier, feel less groggy, and my short term memory has been better.

If you don't have any problems sleeping, you can try using a fidgipod or something similar. Keeping my hands or feet stimulated always helped me sustain conversations and tasks, not sure if it helps short term memory directly though.