What actually happens to you when you drink a cup of coffee? Is chocolate really an aphrodisiac? How do drugs like alcohol and cannabis work? Did psychedelics play a part in human evolution? In this fascinating little book, leading psychopharmacologist Dr. Ben Sessa describes the drugs, legal and illegal, natural and synthesised, from nicotine to endorphins, sugar to antidepressants, that humans all over the world take every day to change their state of mind.