Science in a Tea Cup

Why does tea calm our nerves?

You’ve had a terrible day. The car wouldn’t start and you walked to the bus stop in pouring rain; you spilled coffee on your trousers; your boss was a pain; your deadline is late. You’ve finally dragged yourself home, damp and deflated, and all you want is a cup of tea to calm your nerves and soothe the day away. It works! But — why does it?