The day isn't over when you close your eyes.
Built on the night work your brain does,
as told by John Medina.
All day your brain collects things: faces, words, worries. By night it holds too much. Sleep is how it deals with the pile.
"By midnight my head is a browser with forty tabs open."
You fall asleep and the world gets shut out. The brain switches to slow waves. It is not resting. It is starting its night work.
"I don't remember falling asleep. There's a cut in the film."
Sleep runs in cycles of about 90 minutes. In the early cycles the brain replays your day and saves what you learned: the route, the name, the chord.
"Twenty French words at bedtime. Ten were still there by morning."
Not everything gets saved. Useful and surprising things stay. Small stuff like where you parked gets deleted. Forgetting keeps your head usable.
"Yesterday's parking spot is gone. The new shortcut stayed."
Closer to morning you dream more. Dreams replay the hard moments of the day, but without the stress. The memory stays. The pain fades.
"I went to bed furious about one sentence. By morning it was just a sentence."
By morning the new things are saved and yesterday hurts less. The order is fixed: facts first, feelings last. Sleep too little and you lose the feelings part. Protect the full night.
"The chord I fought all evening just played itself in the morning."
Hover the cloud, the waves, the lattice and the sleeper.