“The brain sits snugly inside the skull, but it's not a completely flush fit - th…” — Jeffrey Kluger

Indeed, the best way to think of willpower is not as some shapeless behavioral trait but as a sort of psychic muscle, one that can atrophy or grow stronger depending on how it's used.

When we're awake, cortisol can fragment memories - one reason eyewitness crime scene accounts are so unreliable. But at night that very fragmentation allows creative recombinations of ideas.

You do not want to talk to me on the phone. How do I know? Because I don't want to talk to you on the phone. Nothing personal, I just can't stand the thing. I find it intrusive and somehow presumptuous. It sounds off insolently whenever it chooses and expects me to drop whatever I'm doing and, well, engage. With others!

In both children and adults, there can be a hard-to-deny link between a robust sense of hope and either work productivity or academic achievement.