I can wake up, drink a can of red bull (10 years ago for reference), and go right back to sleep for another 4 hours, no problem. I haven't noticed a strong corr

I can wake up, drink a can of red bull (10 years ago for reference), and go right back to sleep for another 4 hours, no problem. I haven't noticed a strong correlation between coffee / caffeine and sleepiness. I have however found a really strong correlation between eating and sleepiness. If I don't eat by 8pm, I'm almost unconscious by 9pm. If I sleep then, I'll sleep until 2 then have a hard time sleeping again until 6 or so. Whereas if I eat by 8pm, I'm awake until 2am or thereabouts.