One of the prerequisites of grad school is that you need to drink a lot of coffee. Not because you like it, but because you have to. Coffee is just wonderful. It's about the only addictive substance that you're allowed to consume legally; heck, you can even drive with a BCC (blood caffeine count) of 101. In fact, the DMV advises you to drink coffee to prevent sleeping at the wheel. Surprising, considering that caffeine is more addictive than marijuana[ cite ]. Caffeine has been known to inhibit repair of cellular DNA, and cause a lot of harm to general health of the user. In large doses (more than 250 mg), it can severely interfere with the central nervous system, just like any other drug. Why then do grad students live on coffee? Well, mainly, it's to stay awake. It's not unusual to have 3 homework deadlines on the same day, and this calls for all nighters just to get the damn homework finished. Also, some folks like dear KK have an "all-nighter schedule&qu