What We Know About Dreams

A slow tour of what science has learned about dreams, told to someone on the way to one. It starts at the doorway of sleep, where people who had played Tetris all day saw falling blocks as they drifted off, and goes on through the night as it really runs: down into deep sleep, up into dreaming, four or five times before morning.

Along the way: a graduate student in Chicago who watched his young son's eyes dart under closed lids and found REM sleep; a professor who wrote her dreams down by candlelight in the 1890s; rats replaying the maze they learned, young finches going over their songs, octopuses rippling with colour as they sleep; a song that arrived whole in the night and became "Yesterday"; and lucid dreamers sending answers out of a dream with nothing but their eyes.

The ending, given away now: the oldest question, why we dream, is left gently open, and the first dream of your own night is already waiting somewhere ahead. You do not need to look for it.

The first minute

Let the day be finished now. All of it. The things that went well, and the things that did not. You can set them down beside the bed, the way you set down your glasses or your book. They will be there in the morning. For now, you do not need them…

Why this one works at night

It is a story about the very thing you are about to do, so drifting off partway is not losing the thread — it is the thread arriving. Each section is a small, self-contained wonder you can pick up or let go of, and every one of them is kind: a body that stays still and warm while the mind travels, a dreaming dog on a rug, a bird practising its song in the dark. Nothing in it asks you to stay awake for the end.

“…And behind it, there is another room. Sometimes a whole wing. Quiet. Full of light, or full of old furniture, or simply—”

The kind of sentence people fall asleep during