All right, so perhaps this is rather too grandiose a claim, but I have found a book that unfailingly puts me to sleep when my brain concocts truly terrifying imagery that makes closing my eyes an exercise in desperation. 

Who is responsible for the tome of my somnolence? What book has achieved such status?

Her name is Barbara Tuchman and her book is:

Now, I haven't read her other works. Excellent scholarship lies herein. It does. Outstanding research skills, she displays. Perhaps it is just the subject matter of this book? Although the 14th Century has long been an era of interest to me, it could be her approach that makes my head heavy within a page or two.

She is undoubtedly a fine author. Her publishers think so, anyway, as she has a sizeable body of work to her credit.  Perhaps I just found the one in her portfolio that is overwhelmed by its minutiae?

In any event, I have to keep better tabs on this book.  Give it its own shelf. Right next to my nightstand.  With a chain on it, so I don't lose it again.