How sleep locks in learning
18-04-2014
For many years we saw sleep as a way of ‘recharging our batteries’ and not much more, but boy has that changed. We now know that sleep is an incredibly complex phenomenon with a wide array of vital functions and purposes that are critical for our overall physical and mental wellbeing. Take memory retention and recall. Sleep is essential in these processes. Without sleep our memory suffers, fast.
Memory
We are not yet sure exactly how memory works but there is agreement that it is composed of three main functions. Acquisition is the first and is the process of storing new data in the brain. The second is consolidation, which is the process where the memory becomes stable, where it is filed and catalogued so it can be found again. The third is recall and is the ability to find the data when it is needed. All three of these steps are vital for memory, without them we would remember nothing.
Memory and sleep
While the first and last happen when we are awake, it seems that the middle process, consolidation, happens when we are sleeping. When we sleep the neural connections that are necessary for consolidation strengthen, ensuring that when we need the information later we are able to access it. While there is no agreement on exactly how sleeping makes this process possible, a number of researchers believe that it is connected to the different brain waves that we have as we go through the different stages of sleep that play a role in the formation of particular types of memory.
Types of memory
There are two main types of memory, declarative and procedural. Early research into sleep and memory looked mostly at declarative memory, the memory that is fact based, your knowledge set. It is the memory aspect that is most useful in pub quizzes and trivia games, it is also the memory of your life, the daily occurrences, your meaningful relationships, it is your life story being stored so you can recall it. More and more research is now focusing on procedural memory, the memory of how you do almost everything in your life, from how to ride a bike to how to play a piano and everything in between.
Sleep and the types of memory
With regard to declarative memory, it seems that during rapid eye movement (or REM) sleep the process of consolidation occurs for memories which are emotionally intense, while they think that the pub quiz memories are consolidated during slow wave sleep. Research on procedural memory suggests that REM sleep also plays a critical role in the consolidation of your procedural memory.
Lack of sleep
The amazing thing is that many studies on the topic have shown how little lack of sleep we need to suffer negative impacts on our memory. Tests on non-emotive (i.e. fact based) declarative memory showed that even after only missing one or two hours of sleep people struggled in tests, often scoring half as well as those who had slept well the night between the information acquisition and recall.
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