Those energy drinks you use to jump-start your day are causing health problems for some people.  A new government report says in the last five years, the number of people visiting the nation's emergency rooms because of energy drinks has doubled.  OHSU Toxicologist Doctor Robert Hendricksen says each drink is loaded with as caffeine as 2-5 cups of coffee.  Doctors are seeing more patients with anxiety, headaches, rapid heart rates and irregular heart rates. Those symptoms can be life-threatening if you have an underlying health problem.  With 18 deaths possible linked to the drinks, two U.S. Senators are pushing the FDA to investigate safety concerns.  In the meantime, doctors advise using the drinks in moderation.