Am I the only one who thinks you shouldn't "hack" your sleep. The human body isn't a computer or a program and shouldn't be treated as such.
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?