Epinephrine initiates a signal transduction pathway that produces cyclic amp (camp) and leads to the breakdown of glycogen to glucose, a major energy source for cells. but glycogen breakdown is only part of the fight-or-flight response that epinephrine brings about; the overall effect on the body includes an increase in heart rate and alertness, as well as a burst of energy. given that caffeine blocks the activity of camp phosphodiesterase, propose a mechanism by which caffeine ingestion leads to heightened alertness and sleeplessness.