Sleep

Daniel Lieberman is a professor in the department of human evolutionary biology at Harvard. He says that the notion of "getting exercise" — movement just for movement's sake — is a relatively new phenomenon in human history. His new book is Exercised: Why Something We Never Evolved to Do Is Healthy and Rewarding.

When Pollan decided to write about caffeine, he gave it up — cold turkey. "I just couldn't focus," he says. "I was irritable. I lost confidence." Originally published Feb. 10, 2020.

After wrapping up his book about the potential therapeutic benefits of psychedelic drugs, author Michael Pollan turned his attention to a drug that's hidden "in plain sight" in many people's lives: caffeine.

We tend to think of being asleep or awake as an either-or prospect: If you're not asleep, then you must be awake. But sleep disorder specialist and neurologist Guy Leschziner says it's not that simple.