When I was young and woke at night with a cough or fever, my grandmother would always show up with something for me to take.  Her comment was always, “It’s good for what ails you.”

Like a good soldier, I sat up and drank.  In a matter of minutes I fell asleep, usually for a long time.  When I woke, I generally felt better, though with a slight headache and a dopier than usual feeling!

Recently I uncovered the reason!  Here it is!