The spreadsheet I made tracking the key things I should do each day -- it's been really fantastic.
Here is a breakdown of a breakdown of habits --

Note that the 26th went reasonably well; no outright failures, and basically everything on track.
But buried in there, you'll see, is "Sleep Well" is only at half.
I stayed up later than I meant to -- I got a late dinner and was chatting with Kai very slightly before I should have gone to bed (and I could have just skipped the meal), and thus -- with new energy from food and socializing -- simply stayed up later than I meant to.
So, I slept later than I meant to, then slept in, and my habits started being off. Instead of waking up at 4AM as I had the previous week or so, I got up around noon.
After that, I started on some miscellany before my important work, and then it was later in the day. Feeling somewhat bad to be behind schedule and feeling somewhat yucky on the 27th, I didn't ride it out -- I got some sushi with rice and a lot of fruit, instead of the high-protein high-fat diet I've been eating... and things cascaded from there.
I then stayed up too late once again, screwing the nights sleep schedule, and there is a cascade of effects.
It's interesting to note that, and note it from analyzing the spreadsheet, and the order things built. Had I not gone to dinner at 7PM and gone to bed sometime in the next 90 minutes after that, I'm quite confident the next day would have run well.
Sure, I could have hit the brakes or held the line on the 27th, and that's also worth looking into. But I think sometimes, we underestimate the effects of doing things wrong upstream, and over-estimate how much we can be reflective and use willpower to deal with upstream effects.
Slept too late --> Woke up too late and off schedule --> Didn't start on most important work --> Felt somewhat demoralized and lazy --> Ate some junk --> Stayed up too late again
Noticing that, I broke the cycle on the 28th by just setting minimum objectives to hold the line and scope down. I'll write more about that shortly. But the big takeaway --
Lots of times, low production and "being off" is a result of upstream problems, and fixing those situations is often done better by eliminating the upstream problems instead of trying to use more willpower/reflectiveness/discipline once the poor environment/situation has been built.