Creativity is apparently the internet's flavour of the month. This one is also interesting with regards to the purpose of sleep.
As you start to fall asleep, you enter non-REM sleep. That includes a light phase that takes up most of the night, and a period of much heavier slumber called slow-wave sleep, or SWS, when millions of neurons fire simultaneously and strongly, like a cellular Greek chorus. “It’s something you don’t see in a wakeful state at all,” says Lewis. “You’re in a deep physiological state of sleep and you’d be unhappy if you were woken up.”
During that state, the brain replays memories. For example, the same neurons that fired when a rat ran through a maze during the day will spontaneously fire while it sleeps at night, in roughly the same order. These reruns help to consolidate and strengthen newly formed memories, integrating them into existing knowledge. But Lewis explains that they also help the brain extract generalities from specifics—an idea that others have also supported.
This process happens all the time, but Lewis argues that it’s especially strong during SWS because of a tight connection between two parts of the brain. The first—the hippocampus—is a seahorse-shaped region in the middle of the brain that captures memories of events and places. The second—the neocortex—is the outer layer of the brain and, among other things, it’s where memories of facts, ideas, and concepts are stored. Lewis’s idea is that the hippocampus nudges the neocortex into replaying memories that are thematically related—that occur in the same place, or share some other detail. That makes it much easier for the neocortex to pull out common themes.
“Some people argued that slow wave sleep is important for creativity and others argued that it’s REM. We’re saying it’s both.” Essentially, non-REM sleep extracts concepts, and REM sleep connects them. Crucially, they build on one another. The sleeping brain goes through one cycle of non-REM and REM sleep every 90 minutes or so. Over the course of a night—or several nights—the hippocampus and neocortex repeatedly sync up and decouple, and the sequence of abstraction and connection repeats itself. “An analogy would be two researchers who initially work on the same problem together, then go away and each think about it separately, then come back together to work on it further,” Lewis writes.
Which is all very interesting but there's a major weakness here :
People can be deprived of REM sleep without suffering from any obvious mental problems. One Israeli man, for example, lost most REM sleep after a brain injury; “he’s a high-functioning lawyer and he writes puzzles for his local newspaper,” Lewis says. “That is definitely a problem for us.”
https://www.theatlantic.com/science/archive/2018/05/sleep-creativity-theory/560399/
...and yet, the puzzling exception of the lawyer does not disprove the rule. It merely suggests that there may be other unacknowledged rules in play...
ReplyDeleteI was wondering if perhaps in that case another part of the brain had taken up the same role usually played by REM sleep. Maybe he's constantly daydreaming in court. :P
ReplyDeleteDidn't the Nazi experimented with depriving people of REM sleep? If I remember correctly, they noted that people become stressed, start having hallucinations and ultimately die over the course of a few weeks.
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