My main takeaway is the low fidelity of existing studies and methods.
I found it interesting how small the studies are. Maybe they are challenging to operate at scale? What is the point of even talking about a trial with 43 participants split into 3 groups? That seems little better than the anecdotes presented here.
Also interesting to me that cortisol level and wrist actionography are the only quantitative methods... As mentioned in the article (and intuitively) both seem deeply flawed! Perhaps new methods are the next frontier for this research.