“Have you ever felt like your brain is full? Maybe when starting a new job, or deep in a project. You’re not sleeping enough, even though you're constantly taking in new information. Well, in a way, your brain actually is full.

When you learn lots of new things, your brain builds connections, but they’re inefficient, ad hoc connections. Your brain needs to prune a lot of those connections away and build more streamlined, efficient pathways. It does that when we sleep.

Your brain cleans itself out when you sleep—your brain cells shrinking by up to 60% to create space for your glial gardeners to come in take away the waste and prune the synapses.

Have you ever woken up from a good night’s rest and been able to think clearly and quickly? That’s because all the pruning and pathway-efficiency that took place overnight has left you with lots of room to take in and synthesize new information—in other words, to learn.”