Why is eating chocolate so pleasurable? Can the function of just one small group of chemicals really determine whether you are happy or sad? Does marijuana help to improve your memory in old age? Is it really best to drink coffee if you want to wake up and be alert? Why is a drug like PCP potentially lethal? Why does drinking alcohol make you drowsy? Do cigarettes help to relieve anxiety? What should you consume if you are having trouble staying in your chair and focusing enough to get your work