Both Serrapeptase and Nattokinase gave me dizziness along with severe insomnia with continued use. I later read that they can interfere with GABA and glutamate which could be the cause.
I can’t remember the details but it seemed enough of a link that it wasn’t worth trying for me.
Do you recall how many capsules/times a day you took the Serrapeptase?
I am starting slow - 1 capsule 1x day