Memory and Sleep: Why REM Sleep Might Be the Key to Stronger Memories
Written by Darren Alhabees
Most of us think of sleep as a break, a time when our mind shuts off after a long day. But your brain is actually busy while you sleep. Sleep has two major types: REM sleep and non-REM sleep, and we cycle through both during the night. One important stage of sleep is Rapid Eye Movement (REM) sleep. This is the stage when dreaming is most vivid, and your brain becomes almost as active as when you are awake. Research suggests that REM sleep might play a special role in helping us learn and remember.
It is important to note that non-REM sleep plays a key role in memory. In particular, slow-wave sleep supports memory consolidation. Research suggests that slow-wave sleep helps stabilize newly learned information and supports long-term memory storage (Dudai et al., 2015). Moreover, some studies show that sleep can protect memories from interference. Interference is when new information pushes out or mixes with older information (Jenkins & Dallenbach, 1924; Abel & Bäuml, 2014). This means that after learning something new, sleep can help keep that memory from getting lost or confused with other things you learn later by reducing interference. Both REM and non-REM sleep protect individuals from interfering stimuli.
More recent work suggests that REM sleep may be particularly relevant when learning becomes difficult. When new learning has a lot of interference, REM sleep may help by reducing the competing information, allowing memories to be processed without further interference. Hence, REM sleep protects learning under high interference (McDevitt et al., 2015).
REM sleep seems to be especially helpful when the information you learn fits into something you already know. For example, one study found that melodies that followed a familiar musical pattern were remembered better after REM sleep. In other words, REM sleep may further strengthen ideas that already fit into existing knowledge (Durrant et al., 2015).
There is also evidence that REM sleep helps us process emotional memories. A large review of studies found that REM sleep supports both emotional (e.g., remembering an upsetting or happy picture) and non-emotional (e.g., remembering neutral details, like the location or the background of the picture) types of memory, and that the emotional areas of the brain are active during this stage (Genzel et al., 2015). Another study showed that people remembered emotional pictures better after a night with more late-night REM sleep. This suggests REM sleep may help process and store emotional events in a meaningful way (Groch et al., 2015).
However, not all REM sleep research is about emotions or interference. Some work suggests that REM sleep may even help us learn new rules or patterns (e.g. recognizing the order or structure that information follows). One study found that the amount of time people spent in REM sleep predicted how well they learned complex rules (e.g., learning the grammar of a made-up language), especially when the information did not match what they already knew (Richter et al., 2023).
These findings show that sleep does much more than give us dreams and quiet rest. It may protect memories from interference, strengthen information that connects to what we already know, and help us process emotional experiences. While researchers are still studying exactly how this works, what is clear is that sleeping may be one of the most powerful tools we have for learning and memory.
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References
Abel, M., & Bäuml, K.-H. T. (2014). Sleep can reduce proactive interference. Memory, 22(4), 332–339. https://doi-org.ezproxy.kpu.ca:2443/10.1080/09658211.2013.785570
Dudai, Y., Karni, A., & Born, J. (2015). The consolidation and transformation of memory. Neuron, 88(1), 20-32.
Durrant, S. J., Cairney, S. A., McDermott, C., & Lewis, P. A. (2015). Schema-conformant memories are preferentially consolidated during REM sleep. Neurobiology of Learning and Memory, 122, 41–50. https://doiorg.ezproxy.kpu.ca:2443/10.1016/j.nlm.2015.02.011
Genzel, L., Spoormaker, V. I., Konrad, B. N., & Dresler, M. (2015). The role of rapid eye movement sleep for amygdala-related memory processing. Neurobiology of Learning and Memory, 122, 110–121. https://doi-org.ezproxy.kpu.ca:2443/10.1016/j.nlm.2015.01.008
Groch, S., Zinke, K., Wilhelm, I., & Born, J. (2015). Dissociating the contributions of slow-wave sleep and rapid eye movement sleep to emotional item and source memory. Neurobiology of Learning and Memory, 122, 122–130. https://doi-org.ezproxy.kpu.ca:2443/10.1016/j.nlm.2014.08.013
Jenkins, J. G., & Dallenbach, K. M. (1924). Obliviscence during sleep and waking. The American Journal of Psychology, 35(4), 605–612. https://doi.org/10.2307/1414040
McDevitt, E. A., Duggan, K. A., & Mednick, S. C. (2015). REM sleep rescues learning from interference. Neurobiology of Learning and Memory, 122, 51–62. https://doi-org.ezproxy.kpu.ca:2443/10.1016/j.nlm.2014.11.015
Richter, M., Cross, Z. R., & Bornkessel-Schlesewsky, I. (2023). Individual differences in information processing during sleep and wake predict sleep-based memory consolidation of complex rules. Neurobiology of Learning and Memory, 205, 1–13. https://doi-org.ezproxy.kpu.ca:2443/10.1016/j.nlm.2023.107842
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The blog posts are for informational and educational purposes only. The posts should not be considered as any type of advice (medical, mental health, legal, and/or religious advice). All blog posts have been researched, written, and edited by the undergraduate students and alumni of the Lifespan Cognition Lab. As a teaching and research-based lab, we encourage all lab members to help make knowledge more accessible to all communities through these posts.
