This is absolutely key. And likewise, don't feel like the time spent working (especially after hours) is any way to judge your effort. There's little point working each night until 2am if you're operating at 10% productivity. For many people, you'd likely get more done in 30-60 minutes before breakfast while you're fresh.

I get more done between midnight and 1am than I do between 10am and 3pm.

Sure, but the key here isn’t “don’t work late at night”; it’s “know yourself, be honest with yourself, and act accordingly”.

Personally? 90% of the time, if it isn’t done before lunch, it’s not getting done. So, I come in as early as I can and get my heavy lifting done from 7a-11a.

The problem is when you only have a sequential of hard problem and you're currently too tired to start and your boss expects a status report in 2 hours...

In that vein, you may really like The Power of Full Engagement.

"How to Fail at Almost Everything and Still Win Big" by Scott Adams (Dilbert author) also talks a lot about managing personal energy.