It sounds like you’ve not used sugar in your coffee for all these years? If so that would likely explain it.
An exogenous stimulant will bypass the natural function of glucose inducing t4 conversion into t3 in the liver, and its subsequent increased energy production/use in the body. The lack of glucose in such a case is causing the body to retroactively produce glucose via gluconeogenesis by elevating adrenaline and cortisol. This is taxing your liver long term, which is the source of sugar (glycogen) storage — the ability to sleep, fast, and handle things like caffeine is a great determinant of how healthy someone’s liver is, because it indicates how efficient their sugar metabolism is.
Danny Roddy talks about how coffee before bed actually helps him sleep longer because it helps maintain energy production longer — Ray talked about quality sleep actually being a high energy act. You need adequate sugar metabolism for that.
If I had to guess, You are likely suffering from excess adrenaline and/or cortisol production from not getting enough sugar in the diet in relevant proximity to the caffeine intake.
