Thread by @garwboy

Here's something several people asked me recently:

Why can't we remember our dreams very well, if at all?

It's because dreams are *made of* memories. The elements of dreams are *already* stored in our brains. Just... not in that weird configuration

#BrainStuff #SciComm

/1

A lot of stuff goes on in our brains when we sleep, like clearing away the cellular debris built up during the day. But one particularly important process is the consolidating, organising, and general sorting out of memories, old and new.

/2

When a new memory is formed in the brain, it's not just left there. It's linked up to existing memories, depending on relevance, category, stuff like that. And a lot of this happens when we're asleep, like a library that sorts all the new books after hours

/3

Given that we experience and remember a LOT of different stuff during any given working day, our brains have a lot of diverse memories to sort through, and a lot of existing memories to connect with. There's a great deal to work with.

/4

There's also the fact that a memory, as we would think of it, is made up of many different components. Sensory experience, spatial location, emotional and cognitive components. Everything happening in our brain can be incorporated.

/5

Our brain's processing systems can recognise that certain elements of one memory have qualities similar to another, so create a connection to both. But in doing so, it has to 'activate' them, to an extent. And we experience this activation.

/6

This happens with multiple memories at once. So, we end up experiencing a whole bunch of memory elements, old and new, being triggered in really random ways. And so we experience this utterly surreal and illogical series of events, where the normal laws of reality don't apply

/7

That can explain why, despite their utterly bizarre qualities, dreams can often feel so normal and familiar while we're experiencing them; because every aspect of them is *already a memory*, something our brain is familiar with.

/8

And when you consider that we can remember so many things, like mental images from books we've read, or hypothetical scenarios we've cooked up, there's a considerable amount of raw material our brains have for creating dreams. They're inevitably going to be 'unique'.

/9

It's not totally random, though. For instance, if you're constantly worrying about something, like a workplace problem, you'll end up with more memories linked to it. And these will be processed during sleep, so you may end up with recurring dreams.

/10

Basically, if you spend a lot of mental energy thinking about something, it occupies more memories, so you increase the odds of it occurring in your dreams.

/11

Some elements can be increasingly common. E.g. we spend a lot of time attending to and worrying about our teeth, and they're involved in a lot of stress response (e.g. grinding), so the teeth falling out dream is a well known phenomenon

frontiersin.org/articles/10.33…

/12

There's even evidence suggesting that nightmares are a defence mechanism. It's our brain trying to detach the powerful recurring fear/stress clogging up our memory and attaching it to something unrelated, to dilute it, take the edge off

d1wqtxts1xzle7.cloudfront.net/4987004/_2007_…

/13

Of course, if the trauma is too great/recurring, it overwhelms our brain's ability to compensate, so nightmares become recurring. And indicative of deeper problems.

/14

But yeah, that's a big part of why dreams are so hard to remember. They're *already* memories. We *have* remembered them. Just... not in that particular way.

/15

I actually address this at length in my next book, which isn't published yet

But I touch on elements in The Idiot Brain

amazon.co.uk/Idiot-Brain-Ne…

And Why Your Parents Are Driving You Up the Wall and What To Do About It

amazon.co.uk/Your-Parents-D…

/16

Non-amazon links for those books can be found here.

hive.co.uk/Search/Keyword…

/17

Thanks for reading yet another #BrainStuff thread. Is that the last one?

Dream on.

/end