Training induced brain fog - solutions?

To add to Nate’s comment around vitamin D, I was on the borderline for low at my last test and have been supplementing with D3 daily since then. I’ve made some changes to my training composition along with some other modifications and have been doing well even at a pretty high training load for the past 8 weeks and also still able to focus well at work. I’ve been averaging 13-18 hours per week and feeling great.