During deep sleep, the brain exhibits coordinated firing and silencing of hundreds of thousands of cortical neurons, creating large, powerful waves.

“at that point the brain goes into this incredible synchronous mantra chant of these slow waves so the brain waves slow down you go down to maybe just one or two cycles per second very very slow brainwave activity but the size of those waves crashing on the beach of the cortex as it were they are huge and the reason is this go back to the sports stadium analogy let's say that we're here at berkeley and we're playing stanford arch rivals yeah which hopefully you're gonna kick their butt fingers crossed just make sure there's no band anywhere to be found it always does a terrible descent but at that point they're chanting in unison so it's louder but they're now making the same sound together and you can actually hear what's being said exactly so now in that single microphone you can hear stanford sucks stanford sucks so all of a sudden all of for reasons that we are only now starting to understand the brain coordinates hundreds of thousands of neurons unlike it does at any moment elsewhere in the 24-hour period hundreds of thousands of brain cells all decide to join hands as it were physiologically metaphorically and they all fire together and then they all go silent they all fire together and then they all go science”