I disagree - the more we understand the underlying mechanisms of our body, the better we can get it to perform. It's a bit like saying changing your diet because you know what's bad for you is messing with nature.
Go to sleep early, eat right, don't eat weird shit at night, and you'll feel better. Witchcraft, I say.
And what makes your doctor the authority on sleep? They inevitably get their information from scientific studies not conducted by themselves, and the author of an ebook can do the exact same thing.
There's no reason to disparage the ebook just because it doesn't look like the conventional form of authority.
Then it should cite the sources.
A few don't lead anywhere, guess that's a symptom of linking out of a two year old ebook?