Seriously, caffeine hits everyone so differently. My friend can drink espresso right before bed and still pass out, but if I have tea after lunch, I'm up until 2 AM. Bodies are weird like that, I guess.
Man, that's so true. My buddy used to down cold brew at like 4 pm and swear it didn't touch him, just like skyler_reed's friend. Then he'd wonder why he was just lying in bed for hours, his brain racing about nothing. He finally swapped it for herbal tea for a week as a test. Said he was asleep before his head hit the pillow on night three. He totally underestimated his own caffeine sensitivity.