What time of day are you least instrumentally rational?
(Instrumental rationality = systematically achieving your values.)
A couple months ago, I noticed that I was consistently spending time in ways I didn't endorse when I got home after dinner around 8pm. From then until about 2-3am, I would be pretty unproductive, often have some life admin thing I should do but was procrastinating on, doomscroll, not do anything particularly fun, etc.
Noticing this was the biggest step to solving it. I spent a little while thinking about how to fix it, and it's not like an immediate solution popped into mind, but I'm pretty sure it took me less than half an hour to come up with a strategy I was excited about. (Work for an extra hour at the office 7:30-8:30, walk home by 9, go for a run and shower by 10, work another hour until 11, deliberately chill until my sleep time of about 1:30. With plenty of exceptions for days with other evening plans.) I then committed to this strategy mentally, especially hard for the first couple days because I thought that would help with habit formation. I succeeded, and it felt great, and I've stuck to it reasonably well since then. Even without sticking to it perfectly, this felt like a massive improvement. (Adding two consistent, isolated hours of daily work is something that had worked very well for me before too.)
So I suspect the question at the top might be useful for others to consider too.
Intuitively, when I'm more tired or most stressed. I would guess that is most likely in the morning - if often have to get up earlier than I like. This excludes getting woken up unexpectedly in the middle of the night, which is known to mess with people's minds.
I tried to use my hourly Anki performance, but it seems very flat, except indeed for a dip a 6 AM, but that could be lack of data (70 samples).