Dear Joaquin,

I love curling up under a pile of blankets at bedtime and waking up refreshed in the morning. You might be surprised to hear that scientists aren’t sure why sleep makes us feel that way.

I talked about how sleep works with my friend Marcos Frank. He’s a brain scientist who works in the Sleep and Performance Research Center at Washington State University.

“Without sleep, we do poorly on a lot of tasks, and our brains and bodies don't work as well,” Frank said. “But why is not entirely clear.”