Sleep - it’s something we all need to do and something many of us could probably do with more of. But what actually happens to our bodies when we sleep – and when we don’t?
We need sleep because our brains reach a point where they just can’t take it anymore. We’ve spent all day responding to stimuli and when we sleep a particular part of our brain simply shuts down and sends us into what is essentially a mini hibernation.
What happens next is actually pretty amazing.
When we sleep, four key things happen.
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The first is restoration. Sleep gives our body a chance to focus on things we don't focus on when we’re awake. The body is doing so many different things throughout the day - our metabolic demands, for example, will increase throughout the day with all our physical activities, whether that is work or study. When we sleep the body starts to redirect that energy towards areas that need restoration, and it gives the body a chance to repair itself.
The second one is memory consolidation. This is something we know happens, and we know is critical, but we’re still not 100 per cent certain how our body does it. The information of our day actually gets solidified. Memory formation is all about neurons, which are nerve cells in our brains. Neurons communicate with each other in a process called synaptic activity. When we sleep, what our body, or what our brain does specifically, is it actually connects things that are important and then chucks away things that are not so important. Somehow it will recognise and almost prune away those neural connections that we don’t need.
Thirdly there is energy conservation – sleep allows us to conserve our energy to ensure that we have enough when we are awake.
Finally, there’s emotional regulation. Again, this is something we don’t fully understand, but sleep definitely helps us in regulating our emotions. It helps us process our experiences, and people with less sleep definitely have less ability to regulate their emotions.
So, what happens if we don’t get enough sleep?
What we've seen is that people with less sleep will have some sort of cognitive impairment. It’s not like one bad night of sleep will cause you to completely stop functioning, because, let’s face it, we’ve all been there.
But with less sleep our brain misses out on that restoration and therefore has less ability to process a lot of that higher cognitive information, things like decision making. A really obvious example is driving – we know lack of sleep can lead to car accidents, and that's down to the brain having less ability to pay attention during the day.
We also know that sleep deprivation leads to mood changes but there are plenty of significant physiological impacts as well. When people have chronic sleep deprivation it’s been known to lead to various health issues like heart disease and high blood pressure.
It also makes us age faster. Recent research has shown that getting less sleep accelerates the way we age, from our organs to our skin and even at cellular levels.
So, if you want to stay healthy, sharp and youthful, ensuring you get your seven to nine hours of shuteye is the way to go.
Dr Iris Lim is an Assistant Professor of Physiology and Anatomy at Bond University.