A while back I looked at a few chemistry papers on measuring caffeine content in a variety of tea leaves, in the hopes of finding some low-caffeine green/oolong

A while back I looked at a few chemistry papers on measuring caffeine content in a variety of tea leaves, in the hopes of finding some low-caffeine green/oolong I could drink late at night. The impression I got was that there is so much variation batch to batch or year to year (not to mention preparation) that it largely swamps any attempt to say 'Darjeeling has less caffeine than Gunpowder Green'. There may be average differences but it's not too useful to know. Whether Red or Green, that tea could still easily be one that will keep you up if you drink it at 10PM. Ah well. (And decaffeinated teas are uniformly garbage-tasting, so that's no, ahem, solution.)