Every once in awhile I think to myself "one cup of tea couldn't possibly have enough caffeine in it to keep me awake" ...
and I am wrong.
ONE cup of tea CAN and WILL keep me awake.
It is almost midnight on a Sunday night. I have been up since 6 am. I have not had a rest all day. I know that I will be up early again tomorrow morning. I have been tired for the past 5 or so years and I can usually fall asleep pretty much anytime.