<div dir="ltr">Brent in particular, but also anyone looking into chemical representations of mental states: <a href="https://www.science.org/content/article/mentally-exhausted-study-blames-buildup-key-chemical-brain">https://www.science.org/content/article/mentally-exhausted-study-blames-buildup-key-chemical-brain</a><div><br></div><div>It's not redness, but does this count as evidence that my tiredness is the same as your tiredness (save for which brain it is in)?</div></div>