How your brain changes memories while you sleep | Marvin Liyanage

One of the biggest life changes I've made the last years has been prioritizing 8 hours of sleep. Part of that decision was reading Matthew Walker's "Why We Sleep", an easy to understand account of how important sleep is in our lives. I already knew that sleep was important but sometimes it takes learning just how bad sleep deprivation is to convince you to change a habit, especially in a world where its so easy to sacrifice sleep for infinite alternatives.

But "Why We Sleep" was more than just a practical reminder, it was full of fascinating research like the fact that if you pull an all-nighter for a test you lose up to 40% comprehension.

I started researching for this video planning to share insights from the book, but found something else that peaked my curiosity...

Our brain isn't just saving memories when we sleep... it's changing them.

Up until now we knew that sleep was crucial for learning. But we didn't understand how REM sleep (the phase of sleep that includes dreaming), and deep slow-wave sleep contribute together to edit memories. New research shows that while both are important for memory consolidation (saving new learning to long term storage in the neocortex), higher proportions of REM sleep in comparison to slow-wave sleep were associated with remembering less specific details and more broad concepts. This is likely to be the brain's way of turning specific memories into abstract schemas, allowing you to apply the learning in many situations in the future.

The brain acts as an editor during sleep:

1. strengthening connections it wants to keep and weakening others

2. abstracting specific details into key takeaways

3. consolidating memories across neurons in the neocortex and weakening connections to the hippocampus to free up short term memory.