It's true that Seth tried all sorts of wacky self-experiments, but it's worth keeping in mind why. Most of them were inspired by the fact that he wasn't sleeping well. He tried all these odd magical remedies - standing on one leg, "morning faces" and nighttime honey are a few I recall offhand - because he had a medical symptom: the inability to sleep well, for which he could find no satisfactory conventional remedy. So he started collecting statistics while trying unconventional remedies, some of which seemed to help.

So perhaps what finally killed Seth relates not to his experimental treatments, but to whatever underlying preexisting conditions inspired him to invest such effort. Seems worth considering, anyway.