Once certain information is learned and processed in the brain, the information is more likely to be retained if a short daytime nap is taken.
A recent study tested 33 healthy individuals for memory, and its connection to sleep. There were 11 males and 22 females, averaging an age of 23.3 years. All participants were given information and tasks to memorize that fall under the category “declarative memory.” Declarative memory includes book and visual study, such as textbook learning and diagram memorization. This is opposed to “procedural memory,” which accounts for things like muscle memory and certain physical skill sets. The study did not address the connection between midday naps and procedural memory.
After learning the declarative memory tasks, which included memorizing words, a diagram and a maze, 16 of the participants took 45-minute non-REM naps, while the other 17 remained awake. When tested later, the trend was that those who took naps remembered their declarative memory tasks better than those who stayed awake.
One important condition stressed in the study was that the tasks had to be learned thoroughly before sleep in order for the nap to have any measurable effect. “These results suggest that there is a threshold acquisition level that has to be obtained for sleep to optimally process the memory,” says study author Dr. Matthew Tucker. In other words, a nap will not allow one to acquire, or retain, unlearnt or poorly learned knowledge that had been recently studied. “The importance of this finding is that sleep may not indiscriminately process all information we acquire during wakefulness, only the information we learn well.”
The conclusion, that a short midday nap may help one retain learnt knowledge, should have a significant impact on those individuals devoted towards gaining and retaining knowledge, such as students. Finding 45 minutes to sleep during the day could potentially save hours of relearning material.
Source: Defeat Diabetes Foundation: Tucker, Matthew. Fishbein, William. Sleep. “Enhancement of Declarative Memory Performance Following a Daytime Nap Is Contingent on Strength of Initial Task Acquisition.” February 1st 2008