The Better You Sleep, The More You Forget (But Wait — That's A Good Thing)

Sleep and memory: We know the two have a direct relationship (inadequate sleep decreases brain activity and limits access to learning, memory, and concentration1), but are you familiar with how, exactly, your shut-eye plays a role? 

Apparently, it's not that a lack of sleep impairs your ability to remember—according to neurologist and Alzheimer's researcher Scott Small, M.D., a lack of sleep actually creates "too much memory." This, as a result, can crowd your brain space and make it easier for the important stuff to slip through the cracks, thus harping on your memory. Small explains the phenomenon below. 

"One of the main purposes of sleep is to trim down our memories," Small says on the mindbodygreen podcast. It's an idea introduced by molecular biologist, neuroscientist, and Nobel Prize winner Francis Crick, Ph.D., who proposed that we sleep in order to forget2; meaning, we sleep so our brains can remove unnecessary information. 

Take a moment to picture your brain as a vast, open field—your memories as the grass poking out from the earth. Sleep allows you to "mow" the lawn and trim down the unnecessary bits that make the field appear cluttered and misshapen. 

See, your brain encounters thousands and thousands of pieces of information every single day, most of which you don't even realize you're processing. "Your brain is very good at remembering a thousand details, and most of them are not really critical for your life," adds Small. Just like the overgrown bits of grass, these memories are extraneous–and if they accumulate on the field over time, they can make the foliage very ugly. 

When people don't get enough quality sleep, their brains are unable to crop these extra memories and hold on to only the important stuff—which is why lack of sleep has been associated with suboptimal working memory1. "Their brains are static with information," says Small. "They can't think clearly." 

The theory makes sense: Sleep is crucial for rejuvenating all the cells in your body and giving them a chance to repair themselves; it's only fitting that time spent dreaming could also help fine-tune your memories. To help enhance your snooze, we suggest taking a peek at our master list of quality sleep tips: the right temperature, sleep schedule, and even bedtime snacks can all make a difference.  

Sleep is crucial for a number of functions in your body, one of which is to help trim down your memories. We know from research that a good night's sleep is important for supporting memory and learning, but Small gives us a glimpse into the specific mechanisms why. The bottom line? Memory has a sweet spot; you don't want to hold on to so much info that it overcrowds your psyche, and sleep plays a significant role in the cleanup.