This would be a lot better if they cited their sources. As it stands it’s interesting but a bit too easy to dismiss as SEO fodder.
The point isn't SEO, we're trying to get people to change their thinking around how we approach sleep.
There is links to research in slow-wave enhancement on our website, but the entire post "could" links to references.
But I take your feedback, and I'll be more conscious of adding links to references in future posts.
General best practice is to link to the sources that you have used. You don’t have to wonder what people might or might not read.