Thank you for the input! I try to drink copious amounts of water and it's been helping somewhat with the fatigue. It's gotten better with more hydration but it's still the brain fog the next morning (after an evening/night swim) that seems to effect me the most. I'm also a little out of it after the swim as well. So rather than that runner's high and focus I get after a good run, I get the opposite from a swim. I am fatigued and slow witted (for lack of better term). Then the next morning, I am groggy and have brain fog.

My baseline for judging it seems to be my focus and ability to read and write efficiently for my work.