That's not easy to sum up, if it was possible to sum up a book in 1 paragraph, I wouldn't have to recommend a book. It's one of the best that popularizes science around sleeping, I'm sure there are others.

But since you asked - https://tylerdevries.com/book-summaries/why-we-sleep/

Sorry to be that guy, but that's not how sleep works and your calculations are off and not usefull. It's better than not caring about sleep at all of course, and might help somebody who simply just doesn't sleep enough, so it's good you made it anyway.

For anyone having sleep issues, please read Why we sleep if you consider your problems mild, or visit sleep centre or consult your doctor if it's affecting your day-to-day functioning.