It's not a peer-reviewed controlled study, of course, but HN isn't a scientific journal. In my view the post is clearly substantive enough for a general interest site.

There's such a thing as a substantive anecdote, and self-observation and self-experimentation have a long and noble history. It's wrong, of course, to draw hard scientific conclusions from such a piece, but it's not wrong to read one, nor to write one, nor to do this kind of experimentation, nor to find it interesting. Plus there's a hacker angle in the DIY aspect.

That's my take on it, anyway. I thought it was cool, and I hope that HN readers are smart enough not to draw the obvious bogus conclusions.