Coffee has one of the fastest reaction times of any product, producing measurable enhancements in mental acuity in as little as ten minutes. It's ability to increase alertness can have interesting effects on sleep patterns. For some coffee prevents sleep. Others report going to sleep quickly and having intense and dramatic dreams producing a pleasurable experience and the ability to remember the dreams in great detail. Coffee improves performance in sports .
Coffee improves endurance.
Coffee helps some, especially elderly people, regulate blood pressure. Dentists report that coffee reduces cavities by fighting plaque causing agents. Only in excessive use, apparently. Two to four cups a day seem to be well tolerated by most of us. More than 6 cups a day can possibly increase blood pressure, increase hypertension, over stimulate gastric secretions, can trigger panic attacks in some who are susceptible to them.