Surprisingly, little is known about sleep and the brain or what happens when we sleep. We aren’t even sure why we need as much sleep as we do: We spend at least a third of our lives asleep. Why do we sleep so long, and why do we need it? I know people who exist on four hours of sleep a night and even wear it like a badge of honour. Let’s take a look at why that badge is misplaced.

With technological advances and developments in neuroscience over the last two decades, we can now measure and monitor activity in the brain. We can measure brain activity both when we’re actively asleep and actively awake. These developments have meant we’ve made considerable inroads in shedding light on why sleep is so important. In particular, the implications on physical resilience, our ability to bounce back, cope with adversity, what it takes to be able to dig deep when we need to. Sleep allows for the body to deal with what’s coming and to feel like we still have something in the tank.

There is a difference between physical and mental resilience, and sleep helps with both.

Sleep enables the body to cope and function better. Sleep helps mental resilience by fortifying things like memory and clarity, reinforcing our ability for the prefrontal cortex to stay in charge. Our prefrontal cortex is the logical thinking brain as opposed to the reptilian brain where we get emotionally drawn into crises or trauma. When we’re drawn into trauma, we feel less able to manage and regulate ourselves, and so we start to experience stress and show signs of anxiety. So, if you want to beat stress and support mental clarity you need a body and brain that is strong and resilient.

Sleep is one of the essential factors contributing to that.

We still don’t know everything there is to know about sleep. We do know that when we sleep it serves a few critical functions that support resilience.

When we sleep, we repair our body and deal with the damage sustained during the day. During sleep, we fortify memories; the brain takes what we’ve learned during the day and converts it from short term memory into long term memory. It also allows us to create patterns or connections with other information that leads us to innovation and insight.

What would your kitchen look like if you didn’t take out the rubbish?

Another vital function of sleep is it allows the brain to carry out rubbish disposal. In the same way that the body uses the lymphatic system to push away all of the rubbish, dead cells and the like, the brain also needs a mechanism to clear the trash.

This function is performed during sleep.

It’s during sleep that the brain gets rid of the cells that have degraded.

No sleep, no garbage removal. It’s that simple, which is why existing on four hours of sleep is no badge of honour.

A chronic lack of sleep results in damage over time because the rubbish is piling up; this happens with sleep disorders such as sleep apnea. It leaves a lot of garbage in the system. Imagine having a garbage bin in your kitchen that you never empty and you keep pouring garbage into it. Another way to look at it is the information going in can’t be captured, and it can’t be processed; like an overflowing cup, it spills over. It’s already FULL.

Your memory is impacted in the same way.

When the brain has been observed under imaging machines, what they’ve found is it remains active, even when you sleep: It never switches off, it never sleeps, EVER! It does, however, switch functions. All of this happens on a cyclical process. If you don’t sleep, there is no other process to get rid of the rubbish. It’s sleep that is the mechanism that allows our brain to be cleaned.

Your brain and body are repairing all the time, but the heavy-duty work is done when we sleep. While your brain doesn’t turn off, it does do different functions in its awake state than it does in a sleep state—the focus shifts to cleaning, to memory consolidation and repair. Notably, there are more areas of the brain that are concurrently active when we sleep.

Sleep is key to good brain health and to resilience. For us to be at our best both physically and mentally, to have mental clarity and perform, we need good quality sleep. Without it, over time, we will sustain long term damage and be far from our best.

So, goodnight and sweet dreams.