A Short Daytime Nap Could Improve Memory
Who doesn’t love an afternoon siesta? There is a time in the day when you just feel like switching off your brain and go off to sleep. But you carry on because of an over-riding feeling of guilt. However, now you have got scientific permission to nap in the middle of the day. In a new study published in the recent issue of the journal Neurobiology of Learning and Memory, researchers have found that sleeping for 45 to 60 minutes during the day can result in a five-fold improvement in the memory performance. The research, which was led by Alex Mecklinger from the Experimental Neuropsychology Unit at Saarland corroborates the findings of several other studies done in the past which point towards the beneficial effects of an afternoon siesta.
Power Naps During the Day are Beneficial for Memory
For their research, Mecklinger and his colleagues enrolled 41 people. All the participants were shown 90 single words and 120 word pairs of two totally unrelated words. The participants were asked to memorize them. In the word pairs, unrelated words were deliberately chosen to eliminate possibility of memorizing due to familiarity. After a given period of time, all the participants were asked to reproduce the words and the word-pairs. Once the participants had finished this task, half of them were asked to watch DVDs. The other half were asked to sleep for around 90 minutes.
While the participants were sleeping, researchers recorded their brain activity with the help of electroencephalogram (EEG).
After 90 minutes, all the participants were asked to reproduce the words once again.
Sleep Spindles Formed During Sleep Help in Better Memory Consolidation
The researchers observed that when the participants retook the test, the ones who had taken a nap for 90 minutes performed five times better than the participants who watched DVDs. In fact there memory recall was as good as that seen before the nap. It was also seen that there was an increased formation of sleep spindles in the EEG of the participants while they were asleep. Sleep spindles are a record of sudden bursts in the activity of the hippocampus present in the brain. These increased bursts are related with memory consolidation.
Short Sleep Helps in Improving Associative Memory and not Item Memory
According to researchers, a short nap does not help much with item memory, the memory that helps us in remembering phone numbers, etc. However, it significantly improves associative memory, the memory that helps in remembering links between unrelated things. That is why, the participants who took a short nap before they retook the test could reproduce most of the word-pairs correctly.
Short Napping Helps in Re-Organizing Memory
An earlier study published in the journal Neurobiology of Learning and Memory found that taking a short nap not only helps in re-organizing memory but also helps in linking information stored in the brain in a manner that it can be retrieved easily at a later stage.
In that study, 31 participants were asked to memorize 2 sets of photographs, each having a face-object pair. The object remained the same in both the photographs but the face was different. The participants were asked to either take a nap for 90 minutes or watch videos unrelated to the task.
After the break, the participants were asked to recollect the face-object pair and were also asked to remember the two faces associated with the same object. This way, both direct and indirect memory was tested.
Here also, it was seen that the participants who took a nap performed much better than the participants who watched videos.
Therefore, one can safely conclude that taking a short nap during the daytime is not a crime. Rather, it is a way to recharge your memory cells so that your performance is improved.
“Nap sleep preserves associative but not item memory performance,” by Alex Mecklinger, et al. Published in the journal Neurobiology of Learning and Memory on February 27, 2015, accessed on May 6, 2015. Retrieved from: http://www.sciencedirect.com/science/article/pii/S1074742715000362