The Earth is tilted on its axis creating yearly swings in day/night hours, climate, etc. To create a consistent life for our circadian rhythm: Find the solar noon for your longitude at June 13 (a zero point date in the equation of time) and schedule wake/sleep around that time. Solar noon is not exactly local noon, especially when daylight savings is involved. Can use a calculator like suncalc.org (this site uses "Culmination" to mean solar noon).
Days may be shorter in winter and longer in summer but staying awake/rescing the same number of hours no matter the time of the year is equalizing the body in an unbalanced world. If this is too complicated can just use 12:00 standard time and 13:00 in daylight savings time for your solar noon. The solar noon here is about 18:30 universal time and the solar midnight is 6:30. I decided how much I want to be awake/sleep and aligned it with the reference point. Will see how much sleep I really need after adjusting back more to the sun's rhythm.
To give you an idea for how much wake/resc you may want these are the average day/night hours at the equator:
9h30m night
1h15m morning twilight
12h daylight
1h15m evening twilight