There is also the opposite effect, where a beneficial substance becomes harmful above a certain threshold (hormesis): https://en.wikipedia.org/wiki/Hormesis ht

There is also the opposite effect, where a beneficial substance becomes harmful above a certain threshold (hormesis): https://en.wikipedia.org/wiki/Hormesis https://en.wikipedia.org/wiki/Hormesis For example, a very small amount (0.5-1 mg) of melatonin helps you sleep, but a large amount can keep you up. Probably not what the author had in mind, but there's a funny thing where sometimes having bigger and bigger problems (or physical pain) makes the previous problems go away. At least temporarily.