Margen
Sleeping too little doesn't gift you extra hours: it lends them to you and collects with interest. That's the thesis Matthew Walker, a neuroscientist at Berkeley, develops in "Why We Sleep."
His central idea: sleep isn't dead time, it's work on another shift. While you sleep, the brain consolidates what you learned during the day by moving memories from the hippocampus (the temporary store) to the cortex (the lasting one), regulates your emotions, and does its housekeeping. Sleeping before you study prepares the ground; sleeping afterward stores the harvest.
Most adults need between seven and nine hours, and chronically cutting them short takes a toll on memory, mood, and immunity. If you want to perform better tomorrow, today's most productive decision is shaped like a pillow.