One important part of language learning is to make associations among new words. This requires consolidation, a process can strengthen memories and make them stable.
Although consolidation usually happens during overnight sleep, a recent study published in Brain and Language shows that an afternoon nap can boost memories too.
In the study, young adults learnt German word-pairs. Some pairs were high-rewarded, i.e. participants could get lots of money if they remembered the pair. Other pairs were low-rewarded, i.e. participants got little money if they remembered the low-rewarded pair.
Participants’ memories about words were tested immediately after learning and after an afternoon nap (maximum 1.5 hours).
The result showed that before taking the nap, participants remembered the low- and high-reward word-pairs equally well. However, after the nap, participants remembered the high-reward pairs much better than low-rewarded pairs.
This suggests that a nap can selectively maintain items in memory when the items are related to high motivation.
In the brain, researchers found a correlation between memory scores of high-reward pairs and brain activity called sleep spindles.
A sleep spindle is a burst of oscillatory brain activity visible on an EEG during sleep. It is generated from interactions between the thalamus and the cortex.
Sleep spindles are associated with integration of new information into existing knowledge. They are also related to remembering and forgetting.
Researchers suggest that the current finding has practical implications for educational settings, especially for second language learning.
For example, students don’t need to study late in the evening before sleep to get memory consolidation. Instead, They can learn new words in the morning, take a nap in the afternoon, and then have a vocabulary test.
Citation: Studte S, Bridger E, Mecklinger A. (2016). Sleep spindles during a nap correlate with post sleep memory performance for highly rewarded word-pairs. Brain and Language, in press. doi:10.1016/j.bandl.2016.03.003
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