I'm drinking 5,6,7 idknw coffee's strong espresso and still manage to sleep. We are all very different.
Discussion
That is a lot!
Yes, I know some people who get some bad effects even after one coffee, so they rather drink tee.
I have no special problem. I can also sleep. Even after the coffee. But I heard that the REM phase will be shorter if you drink coffee, so you won't rest as you would without coffee.
I don't know how it works for me, that is why I thought to give it a try. Let's see.