I drink around a litre of black coffee a day now. It's the other way around for me: I sleep better (i.e. I feel better / less groggy the next morning) if I drin

I drink around a litre of black coffee a day now. It's the other way around for me: I sleep better (i.e. I feel better / less groggy the next morning) if I drink coffee at the evening. Sometimes I even drink coffee at 11pm. ¯\_(ツ)_/¯ Honestly, I'm not sure if coffee even helps to "stimulate" me at all. It certainly lowers the feeling of stress and helps me keep a clear train of thought, though, even if that may be placebo effect. And it's something else than water to drink.