Why We Sleep

Why I'd hand it to you

Matthew Walker is a sleep scientist, and his message is blunt: most of us don't get enough sleep, and it costs our memory, mood, immune system and long-term health. He explains what happens in the brain at night, including what dreams may be doing, and makes a strong case for treating rest as a priority instead of a luxury. Now the caveat. Other researchers have pointed out that some of his numbers and claims go further than the evidence, so read the scariest stats with a grain of salt. Light sleepers already anxious about it may come away more stressed. The big point holds up, and it is a good nudge to stop treating late nights as free.

— Matt Jordan