Given studies associating positive health outcomes with 2-4 cups a day (no idea what defines a cup), would the implied extrapolation here be that a small amount of caffeine during sleep is helpful (holistically)?
There are plenty of studies showing X is good for your health (in moderation, of course!), usually all funded by companies selling X.
Got milk?
By the way, decaf coffee appears to have the same flavonoid content as caffeinated.