...and 8+ is ideal. But between being a full-time developer and running marathons, I figure whether it's due to the lack of a genetic mutation or simple necessity is, bluntly, irrelevant. If I get fewer than 7 hours of sleep, I suck at everything, physical or mental.
...all the comments about "Bayesianism is better than Frequentism" or "Why didn't the authors use this Frequentist analysis?" start popping up. Not that I'm advocating for one over the other, just arguing that they're both tools that are often used for the same nail without realizing that you need to hold them slightly differently for them to actually work the way they're supposed to.
I hope a carpentry analogy is acceptable in lieu of a car analogy.