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I finally understand what each phase of sleep “does” for the brain

Ha, just read an article on sleep that opened me a bit. 

I didn’t realize the sleep controversy was more or less over:

Memory consolidation is now well known as the prime reason why we actually need sleep.

Metabolism only drops 5-10% when we are sleeping, so it’s kind of tough to argue that we’re conserving a lot of energy by sleeping.(Wikipedia cites an additional source on this.)

So there are 3 phases of sleep - non-rem or light sleep, REM sleep - where you dream, and deep sleep - from which it’s hardest to wake.

The same article said that non-rem sleep was useful for scrubbing short term memory and getting our brain ready to learn again. In contrast we know REM sleep is important in long term memory formation.

Just read this article that said :

During deep sleep, tissue is repaired and regenerated and you experience bone and muscle growth. Scientists believe that your immune system becomes stronger during deep sleep.

I have to wonder if the brain grows new neuronal connections during deep sleep as well. Ha just found an article that backs me there:

the amount of plasticity (connections between nerve cells) in the brain depends on the amount of deep sleep

So I think I finally understand what each phase of sleep “does” for the brain.

Light sleep is all about getting rid of less important short term memories and putting the brain in a position so that it’s more able to take things in - to work faster. Rem sleep is about remembering what’s important - putting things in long term memory. Deep sleep is about making new neuronal connections - and thus potentially new insights, based on what you’ve learned. Cool.

And all this sleep is necessary so that your brain functions properly. It kind of raises the question of why your brain can’t do these very basic things while it’s awake. Why can’t it do multiple things at once? Why did evolution make it so that these things happened more often during sleep. Perhaps it’s so that the brain when awake could better focus on being awake - active and full of alertness and attention on the task at hand - so that it could work faster than it otherwise could if it had to devote extra energy to the things it does during sleep - like purging unimportant memories, remembering what’s important, and making sense and making new connections based on what it’s learned…

Another question is why deep sleep should come first. I suppose it makes sense that if you’re going to make new connections, you don’t want the day’s short term memory scrubbed first as you want to integrate what you just learned with what you already know.