Covid has completely warped my window of "productive" work. Generally, I now get most of my work done between 2pm and 10pm. Fortunately, the rest of my team has a similar cadence which is why I pinned 9pm as my boundary :)

I previously thought it was complete and utter pseudo science but I've recently started using a near infrared LED light in the morning and evenings and it's immensely helped reinforce a healthy circadian rythm.

5pm. If emergency once in a while, it should be okay for anytime, personally. (I am not in such a position to be contacted for anyway).