We’ve all had the experience of our memory failing us, whether it’s forgetting a name, struggling to remember what you did the day before, or wandering in search of a pair of keys. Before you ascribe that fuzzy memory to a “senior moment,” or chalk it up to the frenetic pace of daily life, try putting your head to the pillow for a good night’s rest: Sleep—how much you get, and how well you sleep—can have a powerful effect on your memory.
When we talk about memory and its relationship to sleep, we’re talking about the intersection of two complicated, dynamic physiological processes that science is still working to understand.
Broadly speaking, we can think about the memory process as having three distinct phases:
Sleep plays a role in helping—or hindering—each of these aspects of memory. Getting high-quality sleep and avoiding sleep deprivation can make a real difference in your ability to take in new information—essentially, to learn. If you’ve ever tried to study for a test or complete a work project while short on sleep, you’ve experienced the obstacles that sleep deprivation can have on memory acquisition. Even a very short period of sleep deprivation can diminish your capacity to form new memories in everyday learning.
One recent study illustrates the possible benefit of sleep to skill learning and the formation of new memories. Scientists studying the neural activity of mice found that a period of sleep immediately after learning a new skill encouraged the growth of synapses in the brain that were specifically related to that new learning. Tested on performance after periods of 1 and 5 days, mice that slept after the initial learning performed twice as well on the newly-learned task than mice that had not slept.
Sleep also affects your ability to recall memories you already made. Research indicates that recall of both short-term working memory and long-term memory of different forms are impaired by lack of sleep. A sleep-deprived brain is less effective at memory retrieval, while staying well-rested can help protect and improve this “remembering” phase of memory.
While both memory acquisition and memory recall are influenced by sleep, it is the middle phase of the memory process—consolidation—that actually occurs during sleep itself. Memory consolidation takes new knowledge you've acquired and stabilizes that information, preserving it for future recall and helping to protect it from disruption or degradation over time. Memory consolidation that takes place during sleep not only secures memory for future retrieval, but it also appears to free up the learning centers of the brain to take in new batches of information during the next waking day. Scientists are still discovering how memory consolidation works during the night, but it’s believed that memory consolidation occurs across several different stages of sleep throughout our rest. The slow brain wave oscillations and sleep spindles that are characteristic of deep sleep (also known as slow-wave sleep), appear to play a critical role in memory consolidation, particularly for forms of memory that involve the brain’s hippocampus. The relationship between REM sleep and memory is especially complicated, and still not well understood. But REM sleep, with its high levels of brain activity and dreaming, also appears to be important to the processing and consolidation of some types of memory.
The large, growing body of research devoted to the relationship between memory and sleep suggests that a routine of sleeping well can have a positive, protective effect on memory.
Both the quantity and the quality of sleep are important to memory function. Here are 3 basic strategies that can help you sleep both longer and better:
When you’re tempted to stay up late for the sake of being productive, keep in mind that you and your memory ultimately will be better served by getting a good night’s sleep. Well rested, you’re more likely to feel better, perform better—and remember more.
Sweet Dreams, Michael J. Breus, PhD
The Sleep Doctor™