I haven’t finished either game, but i agree with everyone else in that Wrath is a much better game in terms of balance and options, and there’s no story overlap that you’d be missing if you started with wrath. If you get kingmaker on sale, the first arc is a decent story in itself and is actually the inspiration for my next campaign, so there’s definitely some enjoyable content in there
Sleep research has moved on from recommending that everyone needs 8 hours or more of sleep. It’s nothing more than a myth now. Everyone is different, and for most adults the amount of sleep necessary in order to be fully rested is considered between 7 and 9, meaning a lot of people are perfectly fine with just 7 hours, and some need even less than that. In fact this review from 2 years ago suggests that we can’t even guarantee someone will be noticeably impaired with 5 or fewer hours of sleep.