Sleep plays a vital role in memory retention and learning. That is because new information is consolidated in memory during the different stages of sleep.
Research in the past decade has made it clear that sleep supports quantitative memory storage as well as qualitative memory representations (1). In other words, sleep not only allows you to store more information but also improves the quality of the information you store.
Below we explore some of the mechanisms that enhance memory retention during sleep.
Sleep before learning
Getting enough quality sleep is important before learning to prepare your brain to soak up new information. Learning pathways are laid down that are essential for short term retention of information.
During Dr Matt walkers TED talk (2), he mentioned that they compared a group with no sleep to a group with a full 8 hours of sleep. Both groups were presented with a list of facts to memorize. They found that the sleep-deprived group had a 40% deficit in learning capabilities when compared to the group that had a full night’s rest. This is concerning when you consider the fact that 40% could be the difference between passing with flying colors and failing miserably.
So why did the sleep-deprived group struggle to make new memories? When both these groups were studied in an MRI machine, it was found that the group with a full 8 hours of sleep had brain activity in the hippocampus that is associated with healthy learning. On the other hand, the sleep-deprived group had no activity in the hippocampus at all.
Sleep after learning
Research suggests that “pulling an all-nighter” before an exam might not be the best strategy for passing.
Sleep after learning is important to hold on to individual facts and commit them to long term memory (3) (4).
The hippocampus is the part of the brain that is associated with short term memory. It serves as a temporary storage unit with a capacity of approximately 16 hours. During deep sleep, memories are shifted to the Cortex which is a part of the brain that acts as a hard drive. Essentially you need quality sleep after learning to “hit the save button” which commits short term memory into long term memory.
So, what is it about the physiological quality of your sleep that stores and enhances your memory?
By placing electrodes on the head of participants (electroencephalography), sleep researchers were able to discover that there are deep and powerful brainwaves that are present during the deepest stages of sleep, called slow-wave sleep (SWS) (5). And it is these brainwaves that shifts memories from a short-term vulnerable reservoir to a more permanent long-term storage site. Therefore, protecting them and making them safe.
Creativity and problem-solving during sleep
Sleep is not only crucial for learning, but research suggests that sleep plays a vital role in creativity as well (6).
Creativity is facilitated by the reorganization of existing knowledge. REM and non-REM sleep facilitate creative thinking in different ways. The replay mechanisms of non-REM sleep can evaluate new rules from previously learned information.
Something very interesting happens during REM sleep which is also known as dream sleep. During REM sleep, new memories are integrated with old ones. Your brain seamlessly tries to match and associate new memories with past memories. This allows us to come up with novel ideas to solve problems in creative ways.
It is the combined efforts of REM and non-REM sleep that boosts the formation of complex frameworks that results in creative thinking and problem-solving.
It is therefore not surprising that some of the world’s most famous ideas were invented in dreams (7). These ideas include Einstein’s special theory of relativity, the shape of DNA, The periodic table of elements and even Google.
Aging and dementia
The study of sleep has now also been rolled out in the context of aging and dementia. It is no secret that as you get older your learning abilities decline (5). What researchers have also discovered is that your sleep gets worse specifically your deep quality of sleep that is associated with learning (8).
By the time you are 70 years old, you only get 5% the amount of deep sleep then when you were a teenager and by the time you reach 80 years, there is almost no deep sleep activity present.
It suggests that the disruption of deep sleep is contributing to cognitive decline or memory decline.
Key takeaways
- Sleep before learning prepares your brain to soak up new information
- Sleep after learning commits short term memory to long term memory
- “Pulling an all-nighter” is not an effective way of preparing for tests/exams
- Creativity and problem solving are enabled by REM and non-REM sleep
- Learning capabilities decline as you get older and quality of sleep reduce
- Disruption of sleep contributes to cognitive decline or memory decline
References
- About Sleep’s Role in Memory. Rasch, Björn and Born, Jan. 93, 2013, Physiol Rev., Vol. 2, pp. 681-766.
- Walker, M. TED. [Online] 2019. [Cited: 8 3, 2019.] https://www.ted.com/talks/matt_walker_sleep_is_your_superpower#t-958407.
- Sleep deprivation causes memory deficits by negatively impacting neuronal connectivity in hippocampal area CA1. Robbert Havekes, Alan J Park, Jennifer C Tudor. 2016, eLife, Vol. 5, p. 13424.
- The memory function of sleep. Diekelmann S, Born J. 2, 2010, Nat Rev Neurosci., Vol. 11, pp. 114-26.
- Old brains come uncoupled in sleep – Slow wave-spindle synchrony, brain atrophy and forgetting. Helfrich, Randolph F. and Walker, Matthew P. 1, 2018, Neuron, Vol. 97, pp. 221-230.
- How Memory Replay in Sleep Boosts Creative Problem-Solving. Lewis PA, Knoblich G, Poe G. 6, 2018, Trends in Cognitive Sciences, Vol. 22, pp. 491-503.
- Dreams and creative problem-solving. D, Barrett. 1, 2017, Ann N Y Acad Sci, Vol. 1406, pp. 64-67.
- Sleep and Human Aging. Mander BA, Winer JR, Walker MP. 1, 2017, Neuron, Vol. 94, pp. 19-36.
