In my last post on Let’s Talk About Dreams! Part One, we talked about the relationship between dreams and REM sleep. This time I’d like to introduce you to another type of sleep. Yes, there are multiple types – in fact, it’s better to take a look at the following picture to explain how there can be more than one kind of sleeping since it can get technical.
As you can see, REM sleep is the state closest to waking.
We have to talk about the deep sleeps too; at stages 3 and 4. These are called slow wave sleep (aka… The deepest kind of sleep that you fall to before coming back up and experiencing REM again). This is a period where your brain is repairing itself from the kind of mental activity you spent during the day. It’s also the time when sleepwalking, bedwetting, and night terrors happen in children (which all include a kind of bodily-control element to them). Both REM Sleep and slow wave sleep serve a very important function: memory consolidation. REM sleep and non-REM sleep have different roles in making sure that the content of your day makes it from short-term memory to long-term memory. Without restful sleep, our memory suffers!
In order to be able to talk about just how that happens, we need to talk about two different types of memory in addition to our two types of sleep.
One type of memory is declarative memory (sometimes referred to as explicit memory or episodic memory). These are the memories that you can talk about casually, like that time you first took a driving test and left your mixtape on and the instructor complimented you on your ability to parallel park and create play lists and you felt like you just raised the bar for driver tests. Or that time in middle school where you totally caught your best friend chewing on a gum eraser from the art room and they lied and told you it was gum and when you asked for a piece of gum they got really defensive and you are sure it was a bold faced lie.
The other type of memory is called non declarative memory (sometimes referred to as implicit memory). These are the memories you rely on academically, such as memorizing a list, remembering how to do math, or remembering things in order, like the alphabet… or your home phone number… or how to tie your shoe. This is the type of memory that matters when you are trying to learn something new and retain it.
REM sleep and Non-Rem sleep seem reasonable to be paired with declarative and non-declarative memory consolidation respectively, but some studies are suggesting they’re actually reversed. Learn more by checking this information out: http://www.ncbi.nlm.nih.gov/pubmed/16647282 or http://www.ncbi.nlm.nih.gov/pubmed/15504332
REM sleep seems to play a bigger role with consolidating the rote memorization, and slow-wave sleep where you don’t dream seems to consolidate memories of what happened during the day, episodically.
Next time I will talk more about consolidation and how you can take advantage of how it works, but for now, think of consolidation as the way a computer tries to save a file, or the way your phone syncs. Because they exist as a transfer. This is why, when you wake up during or at the end of a dream, you start to immediately forget the details of what happened in the dream. Your brain was using that conscious space to move some files around, and knows that what you experienced wasn’t important to its task, even if the meaning of the dream was important (for this, I recommend keeping a dream journal!)
There’s more to be said about learning and dreaming, but it deserves its own blog. Stay tuned!