I have some of those friends too. They can drink coffee at 11pm and sleep at 11.30. Meanwhile I can't sleep until 8 hours after drinking coffee. I don't know wh

I have some of those friends too. They can drink coffee at 11pm and sleep at 11.30. Meanwhile I can't sleep until 8 hours after drinking coffee. I don't know whether this is differing sensitivity to coffee or something else (better production of whatever it is that makes you tired at night perhaps). A clear and curious correlation is this: The same people that can drink coffee late can and do take naps during the day too. That is: if they lie down in the middle of the afternoon, they could sleep for a little while. That's completely foreign to me, I have never in my soon 50 year life been able to take a daytime nap (at least not since I was 5). It's curious that it seems like a related capability, in my small sample.