Turns out there may be a reason for the old motherly advice to make sure you get eight hours of sleep. According to new research getting those hours may be a vital component of our natural learning process.
Our ability to extract general principles from a small number of examples is crucial to language and literacy. In teaching children how to read, for example, teachers introduce sets of words like chop, chin, chest, church, and chess to convey information about how to pronounce specific letters.
This general knowledge can then be applied to new words like chick, as while its new it fits a pattern we've seen before and so we can reliably pronounce the new work. In the later years of primary school, children develop general knowledge about how affixes work.
Through exposure to relevant sets of words like unknown, uncertain, unhappy, children become able to use affixes like -un in new contexts.
This process is vital to our ability to build knowledge.
Newly published research in the journal Cognitive Psychology investigated the brain processes responsible for acquiring this type of general knowledge.
The researchers trained adults on a made up language, in which groups of individual words were bound together by a rule that was not disclosed to participants. For example, study participants learned:
a clinglomb is a small tool used by cat burglars to cling to skyscrapers
a dunklomb is the gadget used by royalty to dunk cookies into tea
a skimlomb is a professional tool which is used to skim the cream off the milk
a weighlomb is the official scale used to weigh boxers before a fight
The team wasn't looking to see if participants learn the individual words, but whether they could uncover the rule — in the above case, the function of — lomb.
We tested this by examining people's understanding of untrained words like teachlomb when they were presented in sentences.
The remarkable power of sleep
The team's key finding was that participants could apply their understanding of the rule (that — lomb means some kind of tool) to untrained words such as 'teachlomb'.
The results were that participants were only able to do this if they were tested some days after training. Participants showed no ability immediately to figure out the patterns directly after training.
As they tested various hypothesis about why this is the case the team uncovered that people only learned the rule if they inserted a period of overnight sleep between training on the rule-based examples.
The findings fit neatly into dual-mechanism theories of memory. These theories argue that rapid learning of individual episodes is followed by a much slower process of integrating that knowledge into long-term memory.
Basically, these processes rely on different brain structures optimized for fast and slow learning.
Critically, these theories and the new research suggest that sleep is a necessary component of the second, slower process.
Their findings support existing research in adults and children that has shown that the brain continues to process new memories during sleep, making them stronger, more resistant to interference and better integrated with existing knowledge.
This research has a clear message for the teaching of language and literacy. It suggests that if teachers want to convey some general linguistic principal, then they must structure the information in a way that encourages learning.
If a teacher is trying to demonstrate use of the suffix — ing, for example, then presenting a child with a spelling list including the words standing, jumping, swimming, kicking, dancing, talking, nothing would be unlikely to facilitate learning.
In short, the work adds to a growing body of research that shows overnight sleep is critical to aspects of language learning. It suggests that key aspects of learning happen long after classroom instruction — and reinforces the importance of proper sleep behavior in children.