Remember to sleep ...

Sleep to Learn and Learn to Sleep

As parents, we all know that sleep is important for our children but do we know how important it is or why it is important? It is, in fact, so important for learning that without the right sort of sleep for the right amount of time, learning that is accomplished during the day is in jeopardy. Sleep is so important that for many children, improving sleep can be the single most effective change they can make to improve learning and retention.

It’s long been suspected that something special goes on when we sleep, but it’s only as recently as November 2008 that we became sure of the relationship between sleep and learning and memory in particular. Publications around this time made clear the biochemical reasons for the old adage, “Early to bed, early to rise makes a person healthy, wealthy and wise.”

The relationship goes something like this and there are three key points. It’s a bit heavy on the neuroscience, but worth setting out in some detail.

The first idea is that our brains our plastic, meaning that they can be moulded and developed, and that this plasticity lasts throughout life. In particular, the plastic nature of the brain manifests itself in the synapses, the connections that link to brain cells together. Synaptic plasticity, means, in part, that one remarkable feature of the brain is that it doesn’t stop growing in childhood then die off gradually, as we believed until recently, but continues to grow, by forming new connections, selectively allowing other connections to be pruned.

Central to this ability of the brain is a chemical called acetylcholine, which plays a key role in synaptic plasticity, specifically in learning and short-term memory. Acetylcholine works by supporting Long Term Potentiation (LTP). This is the brain circuitry that is responsible for learning and, crucially, developing the capacity for future learning.

So, the brain is able to learn and acetylcholine supports LTP, which supports learning. Where do we get this magic chemical? It will be no surprise that we get acetylcholine when we sleep. First though, there is a slight problem! There are other chemicals in the brain that get in the way.

Serotonin and norepinephrine are chemicals that actually suppress LTP. These are actually the same chemicals that flood into a teenager’s system when they are stressed or angry. There is one stage of sleep when these chemicals are controlled, allowing LTP, learning, to take place.

These chemicals are controlled during a stage of sleep called REM sleep – those stages when your body is completely relaxed but your eyes make rapid movements. These are the dreaming stages of sleep. Serotonin is suppressed at these times, providing the conditions for memories to be formed.

So, it seems like we just need to get some REM sleep and serotonin gets out of the way and the acetylcholine is allowed to do its job of supporting LTP. Not quite, unfortunately.

In fact, we go through several periods of REM sleep every night, starting with periods of deep sleep and cycling through lighter and lighter periods until we finally wake in the morning. 

Here’s the problem: acetylcholine is only released during the last stage of REM sleep before waking.

So here’s the second point: Memories, new skills, connections, new potentials are only really developed during the late stages of a night of sleep. Less than 8 or 9 hours sleep for a teenager and they never get to this stage

This means that we must not only remember to sleep, we must sleep to remember.  

It also means that we need to get a full night’s sleep for this remembering to happen:

“… the absence of the chemicals norepinephrine and serotonin – serves a unique function for memory, giving REM sleep a singular role in learning that is not replicable by more waking practice”

Poe, 2008

The interesting point here is the phrase “is not replicable by more waking practice”. You cannot replace the learning that goes on during REM sleep with more work done while awake.

Here’s the third point. What happens if we go without an adequate amount of sleep for days or weeks?

Lack of proper sleep not only stops learning, but actually damages the ability of the brain to learn in future. That’s worth repeating: lack of proper sleep not only stops learning, but actually damages the ability of the brain to learn in future. The effect is long term and takes time to recover from. On the other hand, the effects of a couple of days of less than ideal amounts of sleep can be corrected by extended periods of sleep later.

So, teenagers can catch up at the weekend, but they can’t learn well, if at all, on less than 8-9 hours a night. In short: sleep to learn and learn to sleep!

Richard Dyer

Principal

British International School Budapest

Twitter: @richardmdyer

Email: [email protected]

Reference

Poe, G., 2008, ‘Chemical State of Brain During Sleep Conducive to Strengthening Memories’, abstract 539.13 of presentation to Neuroscience 2008, Washington DC.