It’s the stage of sleep where a day’s memories are processed and stored. Anything that you’ve deemed to be “important” will be cataloged somewhere in your brain while the rest will be forgotten.
This is Your Brain on REM
The scientific theory that sleep in general benefits memory performance is well established, but is has changed over the years.
Early sleep studies claimed that depriving people of REM sleep impairs certain kinds of memory formation, namely declarative memory, the next day.
In addition, studies done on insomniacs noticed that REM sleep was seen to correlate with comparatively higher levels of memory consolidation, most likely compensating for lower levels of Deep sleep.
Since then, the best evidence for memory consolidation during REM comes from neuroimaging (PET) scans.
These snapshots of the brain show that the areas involved with long-term memory and retrieval are actually more active than in waking states. What’s more, the brain’s emotional center is also highly activated, suggesting that consolidation of emotional memories are especially targeted during REM.
Light Sleep is good, too
However, new evidence indicates that the consolidation of memory also takes place outside of REM sleep.
A 2010 study found that subjects who napped AND dreamed of a memory-related task during a non-REM nap–that is, they did not go into REM sleep at all– improved their performance of the task later on.
On top of that, certain features of sleep architecture are now thought to play a role in the overall memory process. Sleep spindles, which typically occur in Light sleep, are now thought to play a role in declarative memory consolidation along with REM.
Don’t let the name fool you; Light sleep is now thought to do a fair amount of heavy lifting so don’t despair when you look at your sleep data.
Hormones for Human Growth
Finally, hormones are now recognized as an important piece of memory consolidation.
Low levels of cortisol–a major stress hormone–are associated with memory consolidation, whereas increased levels impair consolidation. In healthy sleepers, cortisol remains low in the first part of the night–when we have most of our Deep sleep mixed with Light–but tends to increase towards morning.
So while REM sleep still plays an active role in memory consolidation, it’s important to remember that other sleep stages and bodily functions appear to play important roles as well. To keep this process humming along, make sure that you keep your sleep habits in good order.
Your memories will thank you for it.
- Are there any associations between insomnia and memory loss?
- How important is Light sleep?
- The 3 Rules of Deep Sleep
- Is it beneficial or harmful to get more REM and Deep sleep than Light?
- What is stress and how can it affect sleep?