Purpose:

Be able to wake up easily instead of uncontrollably oversleeping, breaking promises, being late, and feeling like a bad person.

Practice:

I get the best results from treating the evening as the starting point of my daily rhythm. I eat my last meal no later than two hours before my scheduled bedtime (even if I don't go to sleep on time). Bed time is scheduled for 23:00. I then start dimming the lights. In the last hour before scheduled bedtime I eliminate blue light by using use colored light bulbs and using night mode on all electronic devices.

I (almost always) get up at the same time every morning, even on weekends, and even if I went to bed late. I always thought this was a stupid idea, but once I was able to pick a wake up time that actually worked for my body, this was hugely beneficial. I get up at 08:00. In the mornings, dehydration can be confused for hunger; I always drink water before eating. Restricting my eating window to an 10-hour period also worked wonders in combination with these other measures. Instead of breakfast, I drink water until 13:00.

If I have any caffeine during the day, it's usually around this time. Now that my rhythm is dialed in, I only occasionally need caffeine earlier than that. Often I don't need it at all thanks to this life hack: I take a 20-minute nap around 8 hours before my scheduled bedtime. For me, nap time is 14:30 (+/- 30 min).

If I miss my nap, I often fight sleepiness until about 17:00 or 18:00, fall asleep way too early, wake up a few hours later, stay awake 'til 04:00, and totally screw up my plans for the next day. People give me shit for napping, which is fine, because they're stupider than I am.