Wake up stupid early in the morning, get drowsy very early in the evenings etc. For a long time due to social pressure/habit I'd just power through the evening drowsiness. That lead to me only being able to sleep six hours or so (due to waking up stupid early), which over time lead to a substantial sleep debt.
Going to bed early helps a lot, but over time it seems like I easily start drifting earlier and earlier. I've recently had some success stabilizing my rhythm using sublingual melatonin when I first waken at 2-3am. Let's me get a couple extra hours of additional quality sleep which is a lifesaver. Wears off quick enough that by 9am or so it's basically out of my system.
I've actually been tinkering/hacking the last year or so on sleep tracking wearables. Initially focused on EEG/HRV monitoring but I'm taking a very modular approach and ultimately want to build a full set of sensors/effectors/etc.
I've recently been experimenting a lot with skin temperature gradients, turns out in the lead up to sleep it's not just blood flow in the brain that is altered [2].
1. https://en.wikipedia.org/wiki/Advanced_sleep_phase_disorder#...
2. https://journals.physiology.org/doi/pdf/10.1152/ajpregu.2000...