the “quarter life” of caffeine is usually about 12 hours, meaning that 25% of the caffeine in a cup of coffee consumed at noon is still circulating in your brain when you go to bed at midnight. That could well be enough to completely wreck your deep sleep.
Sleep quality is just as important as sleep quantity.”
It’s so pervasive that it’s easy to overlook the fact that to be caffeinated is not baseline consciousness but, in fact, an altered state. It just happens to be a state that virtually all of us share, rendering it invisible.