Three things to know:

The key to a long life? Being the richest person you know. Sir Michael Marmot explains what the health gap is and how it affects the poor, the middle class, and even the rich.

If you have a Ph.D., try San Francisco. Researcher Daniel Shoag says educational attainment is increasingly dictating where we live.

There's a hormone that regulates sleep, reacts to blood sugar, and keeps track of racism. Northwestern's Emma Adam makes a good case for getting to know cortisol.