What sleep can do for you

What sleep can do for you

Most of us realise that sleep is important, but that doesn’t mean we are getting consistent, good quality sleep.

If your sleep isn’t as good as it could be, you are not alone, and the 2020 and 2021 lockdowns and disruption to our lives has made sleep an issue for even more of us.

Research carried out by NHS Digital in 2021 found that children and young people have had a particular increase in sleep problems since the pandemic. More than a third of 11-16 year olds reported difficulty sleeping at the time of the research.

The good news is that even if you are not sleeping well at the moment, there are some simple things you can do to improve your sleep.

In this post I’ll be explaining why sleep is so important. I’ll also be looking at how we sleep and in turn, some of the things that contribute to poor sleep.

I hope that by understanding more about how your body helps you to sleep, you’ll be encouraged to make some small changes to your lifestyle to improve your own sleep.


The benefits of good sleep

You probably know that sleep has many health benefits, but did you know it helps with all these different aspects of your health and wellbeing?

• Immunity
• Appetite and weight
• Long term physical health
• Mental health


Your immune system is divided into two parts: the innate and the adaptive immune systems.

The innate immune system is the part of your immunity that you were born with. It’s your first response to any form of injury or illness.

The adaptive immune system learns and develops from the different illnesses and threats that you are exposed to during your lifetime. As such it is also known as the acquired immune system. It provides specific defences to specific infections.

Both parts of the immune system benefit during good quality sleep.

Your body carries out repair and maintenance of your immune system during sleep and also actively fights any infection or injury that your body is dealing with at the time.

Research has shown that a lack of good quality sleep means your body is less effective at fighting off infection. This means you are more likely to pick up repeated infections.

It has also been found that a consistent lack of good quality sleep before or after having a vaccine can impact the effectiveness of that vaccine.

Long term health

Good quality sleep has been directly linked to having a lower risk of developing chronic health problems such as type 2 diabetes. It has also been shown to reduce the risk of developing Alzheimer’s disease.

Sleep has a direct effect on your blood pressure too.

Your blood pressure rises and falls during its 24-hour cycle with a natural period of low-pressure period during the night.

If your blood pressure is high too much of the time it puts more pressure on your blood vessels, heart and other organs. Long-term high blood pressure, or hypertension, increases your risk of heart attacks, strokes and many other health conditions.

Appetite and weight

I’m sure you know that being overweight has a detrimental affect on your health, but did you know that sleep plays a part in your ability to manage your weight too?

Ghrelin, the hormone that stimulates our feeling of hunger is one reason for this.

Research has shown that even one bad night of sleep increases your levels of ghrelin which makes you want to eat more food.

Ongoing sleep-deprivation therefore means feeling hungry more of the time, making it more difficult to make healthy food choices.

I don’t know about you, but I can guarantee I’ll have a craving for toast if I don’t get enough sleep!

To makes things worse, less sleep also reduces the level of the hormone leptin. This is the hormone that tells us when we’ve had enough to eat.

So poor quality sleep means you feel hungrier AND you have more difficulty knowing when you have eaten enough.

As if that’s not enough, sleep deprivation also increases your insulin resistance which in turn increases your risk of becoming overweight and developing type 2 diabetes.

Mental health

I expect you know first-hand that a lack of sleep can leave you feeling irritable, lacking in motivation and less able to deal with difficult situations the next day.

Continued lack of sleep can increase the likelihood of more serious mental health problems such as anxiety and depression.

Deep restorative sleep allows your body to activate it’s parasympthic nervous system. This is where your body needs to be to support your immune system, digest your food properly and generally function effectively. [read a related post here]

It’s a two-way process, as the more you’re relaxed, the more your parasympathetic nervous system is activated, the easier it is for you to sleep well. And when you sleep well the more you can manage your stress levels, relax and so it goes on.

The charity Mind gives more information about this cyclical link between sleep and mental health.


What controls your sleep?

Now we’ve looked at the benefits of good sleep, let’s look at how you sleep and some of the things that can disrupt your sleep.

Your circadian rhythm

The circadian rhythm is your body’s in-built clock. It runs on a  24-hour cycle (almost) and it’s responsible for regulating your sleep.

Light – and the lack of light –  is the key to controlling your circadian rhythm. It needs light each morning to ‘reset’ itself for the day and a lack of light each evening to support sleep.

The cycle is assisted by the release of the hormones melatonin and cortisol.

Here’s how it all fits together.

Light, melatonin and cortisol – how the circadian rhythm should work

Melatonin makes you feel sleepy. Melatonin increases in the evening, stays high during the night to help keep you asleep and then decreases in the early morning.

The rise and fall of melatonin is linked to light.

When your eyes sense a lack of light each evening, a message is sent to your pineal gland to say that it’s dark. The dark triggers your pineal gland to release melatonin to help you prepare for sleep.

Each morning when your eyes are exposed to light, the pineal gland receives the message to stop releasing melatonin. This helps you to be alert during the day.

Cortisol is the opposite of melatonin as it helps you to stay awake and alert. You should have a peak in cortisol about an hour after waking up and then it will gradually decrease during the day.

Light seen by your eyes in the morning stimulates this release of cortisol each day.

You may already know about cortisol as a stress hormone. A feeling of stress can also trigger the release of cortisol. This is key as it is one reason that your circadian rhythm may not be working as effectively as it should be and will be mentioned again in the next section!

When these things work together like this, your circadian rhythm is in harmony with your body. You will be alert during the day and sleep well at night.


What can go wrong?

Problems with sleep can happen when the circadian rhythm is disturbed.

This rhythm evolved hundreds of thousands of years ago for our hunter-gatherer ancestors. Given the difference in our lifestyle today and the lifestyle of a hunter-gatherer, it’s not surprising that so many of us are having problems sleeping.

However, with a bit more awareness of what causes the circadian rhythm to be disturbed, it’s not difficult to introduce some new habits to help get better sleep.

In this post I will just mention some of the key things that can disturb your circadian rhythm and sleep.

If you want a more detailed understanding there are many sources of information available that explain things in more detail. One of my favourites is the book The 4 Pillar Plan by Dr Rangan Chatterjee. I wish all GPs gave their patients’ this information!


As we’ve already seen, light is a crucial trigger for your circadian rhythm.

Humans evolved to be active in the daylight hours and rest, relax and sleep during the hours of darkness.

It’s only since the first world war (1914-18) that electric lights found their way into most people’s homes.

Although humans had access to fire, candles and then gaslights, the effect of their light on our circadian rhythm was less disruptive than electric light.

Electric lights, television screens, computer and laptop screens along with tablets and mobile phones all expose our eyes to blue light.

Sunlight is also a form of blue light.

This means that every time you look at any type of screen, your eyes are sending the message to your pineal gland to suppress melatonin release as it’s not time to sleep.

If you check your phone or have one last look on social media before bed you are disrupting the release of the melatonin that you need to sleep well.



We know that your brain needs to be exposed to darkness to stimulate melatonin and suppress cortisol.

This means that you need a dark bedroom to get good quality sleep all night, as well as less light during the evenings to encourage the release of melatonin.

Unfortunately there are many ways that light creeps into our bedrooms these days.

Electrical devices often have a standby light that stays on all night and electric alarm clocks might have the time illuminated.

What about the windows? Security lights, street lamps and even the moonlight can seep into your bedroom and disturb your sleep.

Our ancestors just had the light of the fire and then complete darkness to help them sleep so we need to try and replicate this in our own bedrooms.


Cortisol and stress

We know that cortisol causes us to feel alert. That’s why there is a natural decrease in our cortisol levels during the day.

We also established that cortisol is known as the stress hormone.

This means that as well as being stimulated by light, cortisol is also released when you feel stressed.

Our hunter-gatherer ancestors experienced stress in a very different way to us. For them it literally was life or death.

They needed cortisol to help them fight or flee from a dangerous situation. The stress response, which you probably know as the fight-flight response, was powerful but short-lived.

Unfortunately, your brains still interprets every type of stress in your life as though it is a life or death situation.

And there are so many things in our modern life that the human brain considers a stress. A ringing phone, a text or email notification, running late for an appointment, an argument or disagreement. And so the list goes on.

Every time you experience one of these stress triggers your body releases cortisol.

Given that our cortisol should be gradually decreasing during the day you can see the problem.


What can you do to improve your sleep?

You hopefully now have a better understanding of what your body needs to get better sleep.

I’m sure you’ll already have come up with some ideas about how you can make some changes each day to help improve your sleep.

Small changes, every day can have a huge and positive impact on your sleep patterns.

If you would like some more guidance then you can read this post on A few ideas for better sleep.

Sometimes there are underlying health problems that can cause bad sleep. If you are concerned that this may be the case it’s important to speak to your GP to rule this out.

If you would like to find out how I can support you to improve your sleep then please get in touch or book a free Discovery Call.

Take care,

Sarah x

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