Book hangover refers to the moment when you've finished a book and you suddenly return to the real world, but the real world feels incomplete or surreal because you're still living in the world of the book.
The book that enables you to have a book hangover is likely to be a book that you could not bear to finish it or let it go. Only when a book that is well-written, thought-provoking and readable or fits your style can it causes the book hangover. Enchanted by the book, we prefer to slow down our tempo to read, think and hang around it even after the ending.
"I have a really bad book hangover today; I could hardly concentrate at work."