Comment by WaitWaitWha

> We know that the subconscious mind is processing information (i.e. “thinking”) all the time, even while we sleep. The evidence for this kind of “sleep learning” is incontrovertible and summarized in my memory improvement book...

No. Just the opposite. A quick search shows majority of the scholarly papers question "sleep learning". Maybe 16 years of new data?

e.g., https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1365-2869....

and, as @joeyagreco noted the link is (might as well be) dead.