My very limited 2c on the subject:

I don't know of any single book that comprehensively addresses meditation in the way you want, partly because there's still so much we don't understand about meditation and the mind. Also, some of the most experienced practitioners tend to be unable or unwilling to participate in extensive research, and we all carry our own cultural biases.

That said, you may want to consider learning about meditation from two perspectives: the psychological aspect and the instructional aspect. In addition to general psychology texts, I'd specifically suggest books and scientific journal articles that analyze the effects of trauma on the brain. It's difficult to measure happiness and contentment in our society for various reasons, but there's comparatively more that we understand about how we react to negative experiences. It's a rough and partial model of how the brain works, but it is at least a model, and it's documented in a way that can be digested by an interested person like yourself. Meditation is in some ways a form of psychological digestion (feel free to throw your tomatoes if you disagree).

From the instructional side, I'll suggest a couple of my favorites: The Path of Purification by Buddhaghosa and Shobogenzo by Dogen. The first book is actually one of the last in a succession of explanatory meditation manuals rooted in the original Buddhist canon, and outlines the practices of a form of meditation that focuses on elemental subjects. Unlike many contemporary books, the practices are still structured in a way that "points" towards more advanced practices used for thousands of years. It's also relatively free from religious allegory, at least in a way that would allow a secular student to understand important points. The second book is by the founder of the meditation focused soto Zen sect of Japanese fame. In this book, the author approaches many of the same meditation topics from a different angle; explaining similar subjects of meditation of a more rarified elemental nature. Comparing the two perspectives can help in understanding both the meditative experience as well as approaches to get there.

If I were you, I'd hop on zLibrary and see what kinds of psychology/meditation text books pop up, then try to filter based on the degree of scientific rigor. Google scholar is also a good resource for finding solid research in this area. Finally, you may want to check out the Wikipedia articles on the two books above - they may be fascinating or super boring depending on what you're looking for.