Best night-time study aid for a student is a keemun or an autumnal darjeeling (since now I have a bundle of it). And, I can still get to bed at a decent hour…maybe 2am or 3am! Haha. But I have never really had a problem going to bed even after a cup of tea. Although, I definitely HAVE felt the effects of caffeine, which are really not good…too many cups of coffee after too little sleep is a horrid idea.