And this, too. I can sleep really well if I am not working on anything that spans multiple days, or if the problem I am stuck on is succinct and self-contained.

And this, too. I can sleep really well if I am not working on anything that spans multiple days, or if the problem I am stuck on is succinct and self-contained. A lack of closure on whatever I was last working on is the root cause for my disturbed sleep. Do you also feel this way, or is there some other source for you?