What Really Happens When You Sleep?

Everybody knows that we sleep to give our bodies rest. But what really happens when you sleep? And why is it so important?

This last great mystery of human biology has been a topic of debate for centuries, but only until recently have we really begun to fully understand it.

So why do you sleep?

We used to ask the question, what is the purpose of sleep? As if it was one single function. That’s the equivalent of asking why are you awake? You’re awake for lots of reasons. The same is true for sleep.

Matthew Walker, Neuroscientist and author of the international bestselling book ‘Why We Sleep’ puts it like this:

To really understand why we sleep, we have to flip the question and instead ask, is there any process in our brain or any tissue or organ without our body that doesn’t benefit from sleep? The answer seems to be no.”

So really, sleep is not just a contributing factor to good health and wellbeing - it's the foundation.

Crowd of sleepy people on a train.

What happens when you don’t sleep enough?

Aside from the obvious fatigue and forgetfulness, we now know that sleeping less than 6 hours a day can have far more horrific consequences.

From Alzheimer’s to cancer, diabetes to depression, even strokes and cardiovascular disease, are all linked to deficient sleep.

A sleep survey in 1942 concluded that the average adult was sleeping 7.9 hours a night. Now that number is closer to 6.5 hours per night during the week for most adults.

To put that in perspective, Mother Nature took 4.4 million years of evolution to program us to need 8 hours of sleep.  We've shaved a whopping 20% off that time in less than 100 years.

No other species in the animal kingdom purposefully neglect sleep - if that's not reason enough to reclaim your right to sleep, here are four more reasons to get the golden 8 hours.

Your muscles might shrink

Regularly pumping iron or dieting? Sleep first. Otherwise, a whopping 70% of the weight you’re losing will be muscle, not fat – undoing all your hard work and sacrifice.

That’s because when you are underslept, your body is more reluctant to let go its supply of energy, rendering your diet ineffective.

Girl preparing to a run.

You’ll burn fewer calories

Feel the full benefit of your runs, swims or dog walks by doing the exact same amount of exercise when you’re well-rested. 

You’ll move more efficiently when you’re not sleep deprived, giving you more stamina and making you less likely to injure yourself - helping you to burn more calories with every workout.

You will never make back the sleep you’ve lost

Your brain can do incredible things, but it can’t store sleep for nights when you’re wide-awake. And lie-ins can never replace the sleep you’ve lost – that’s why they’re such an indulgent hobby. 

It’s biologically impossible to reverse a rubbish night’s sleep, as your brain can’t store sleep in the same way that your body stores energy from food.

Evolution simply hasn’t had time to adapt to a technology and stimulant fuelled post-industrial way of life.

Stressed girl working on a laptop.

It becomes more difficult to store memories and learn new things

When you’re awake, the brain is constantly storing new information. Like learning someone’s name, or where you parked your car. This information is stored in the hippocampus part of the brain – a sort of short-term memory bank similar to the camera roll on your phone.

When the hippocampus becomes full, you sleep, and the short-term memories are transferred to a larger, more permanent storage location in the brain, freeing up the hippocampus for more learning the next day.

This is why when you’re sleep deprived it’s much harder to remember even the simplest bits of information!

So the next time you immediately forget that person's name, it could be a sign you're not sleeping enough.

What can you do?

The answer is simple. Choose sleep and enjoy spending time in your bed.

As it turns out, the secret to a long and healthy life isn’t a secret at all. Sleep is the most powerful elixir of wellness and vitality in Mother Nature’s arsenal.

It enhances your memory and slows down the ageing process. It strengthens your immune system and improves your stamina.

You’ll feel happier, more alert, and less reliant on stimulants like caffeine just to feel normal. It will give you a zest for life you never knew you had.

Read 12 easy ways to sleep healthily tonight and start now. 

Person performing meditation.

A whole lot more than selling beds

Our resident sleep specialist Carl has spent more than 40 years educating people on the importance of sleep.

It’s his belief that people who get the recommended 8 hours of sleep live longer and happier lives. It’s why we won’t rest until you do.

If you haven't seen the video yet, watch it here.