You practice a new piano song for 2 hours (input). Then you sleep for 8 hours. When does your brain actually "save" the song?

Practice creates the weak trace.

But the trace is fragile. If you don't sleep, it washes away like footprints in the sand.

🔊

You learn while you dream.

The Insight: Sleep is not "downtime." It is "save time." Without sleep, the save button is never pressed.

The Strategy: Never pull an "all-nighter" to study. You are typing the document but forgetting to hit Save.

It's true that both are needed. But the "permanent save" action happens almost entirely during sleep.