Daytime Napping Improves Memory




Napping sounds like just the thing for babies and elderly, but even healthy adults can rely on a daytime snooze to improve their mood, alertness, and memory. Napping has been shown to enhance memory performance and counteract the effects of fatigue. Firefighters, doctors, astronauts, pilots and other professions that handle complicated procedures for long hours are often advised to take a nap during rest time. While many studies support the notion that napping strengthens existing memory, a recent study suggests that napping also reorganizes memory and links information together to form memory networks for easy retrieval at a later time.

A recent research article published in Neurobiology of Learning and Memory examines the role of daytime napping in memory processing. Thirty-one healthy participants are given a task to memorize two sets of photographs called “face-object pairs,” in which the same objects appear in both sets. That is, each object is associated with two faces: one from each set. A group of the participants is allowed to nap for up to 90 minutes, whereas the other group must remain awake and watch a non-arousing video about topics unrelated to the memory task. After the nap group fully wakes up and joins the non-nap group, all participants are tested to see if they remember the face-object pairs. In addition, participants are asked to match the two faces that are associated with the same objects. For instance, if face A is paired with a teacup, and face B is paired with a teacup, participant has to match face A and face B in order to score.

The nap group performs better than the non-nap group at memorizing face-object pairs. More importantly, the nap group also performs better than the non-nap group at matching faces associated with the same object. The nap group even scores higher as the nap gets longer. Since the participants directly learned only the face-object pairs, they have to perform face-matching task using indirect, or relational memory. Therefore, daytime napping not only enhances memory, but also helps reorganize and combine memories with common features together for later recollection.

Short daytime napping is consisted solely of the dreamless non-rapid eye movement sleep (NREM), which also represents up to 80% of nighttime sleep. Research studies suggest that interaction between the neocortex and the hippocampus in the brain is important for forming long-term memory peaks during NREM sleep. Therefore, daytime napping allows our brain to organize and consolidate memory for better performance while we are awake. Nighttime NREM sleep is likely to have a similar beneficial effect on memory. All in all, it appears that the best way to cram for exams is to include a full night’s sleep or, at the very least, a restful nap.

References

Ficca, G., Axelsson, J., Mollicone, D., Muto, V., & Vitiello, M. (2010). Naps, cognition and performance Sleep Medicine Reviews, 14 (4), 249-258 DOI: 10.1016/j.smrv.2009.09.005

Lau, H., Tucker, M., & Fishbein, W. (2010). Daytime napping: Effects on human direct associative and relational memory Neurobiology of Learning and Memory, 93 (4), 554-560 DOI: 10.1016/j.nlm.2010.02.003

MOLLICONE, D., VANDONGEN, H., & DINGES, D. (2007). Optimizing sleep/wake schedules in space: Sleep during chronic nocturnal sleep restriction with and without diurnal naps Acta Astronautica, 60 (4-7), 354-361 DOI: 10.1016/j.actaastro.2006.09.022

Chalita Thanyakoop, PhD

Chalita Thanyakoop, PhD, currently works as a postdoctoral researcher in a microbiology laboratory at University of California, Berkeley. She holds a PhD in biochemistry.
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