Specifically to take before bed, I notice every type of nmda antagonist (memantine, dxm and even alcohol) creates some kind of rebound in me when i wake up in the morning. Where I feel refreshed and literally feel as if my brain is running on higher voltage (in a good way and not excitoxicity).
Now the obvious one would be magnesium (not potent enough), so Im looking for somewhat stronger that can be used long term but doesnt carry substantial side effects such as the hardcore stuff like 3meo-pcp and god knows what else.
I know isochroma (I know dont laugh) had some sort of protocol aswell where he would take ~30mg worth of DXM before bed.