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Sleep - why is it so important?

Sleep loss affects our susceptibility to infections, metabolism, and mental health. Poor sleep habits are also a significant risk factor for type 2 diabetes. Sleep interruption modulates hormones such as cortisone and melatonin, subsequently affecting glucose metabolism

The Lancet

Waking up to the health implications of poor sleep habits (2019)

We all know that we feel better after a good nights sleep and that a lack of sleep can leave is irritable, clumsy and generally feeling run down. But a lack of sleep is more serious than that. Sleep is a fundamental aspect of our overall health and well-being. Without a good sleep, nothing else works as well! Let's look at why that is and what we can do to support proper sleep!

The quote above from The Lancet shows the significant impact of sleep loss on overall health but what does that really mean?

Weakened immune response

Increased anxiety, stress, depression and mood disorders

Increased risk of metabolic conditions


Type 2 Diabetes

What happens as we sleep?

Firstly what exactly happens to us whilst we are sleeping? Do we just hit the pillow and wake up several hours later feeling refreshed? When we go to sleep, our body then starts working very hard. A lot happens and your body is very busy whilst you sleep

You sleep in cycles or waves – REM and NREM but these are broken down further NREM has 3 stages of sleep, nothing is straight forward in our bodies!

In a typical 8 hour sleep you will go through 4-6 cycles of sleep

As you sleep one of the most important aspects is that your body is restoring itself ready for the next day the most famous theory (Oswald) on this is that REM sleep is important for brain restoration and Deep sleep for body restoration.

Another sleep theory is that whilst we sleep, we are able to process emotions – these can be monitored in times of stress by keeping a dream journal – 75-95% of dreams are thought to have an emotional context.

There are several other health associations with poor sleep.

Sleep and Heart Health

Poor sleep is an independent risk factor for Coronary Heart Disease (CHD)– during NREM stages of sleep our heart rate, blood pressure and breathing all slow thus reducing pressure on our heart.

Nocturnal dipping refers to the fact that our blood pressure drops by 10-20% during our sleep, this is important for our cardiovascular health – if you have a lack of sleep or disturbed sleep your blood pressure doesn’t get the change to ‘nocturnally dip’ and you have instead, night time elevated blood pressure

A prolonged lack of or frequently disturbed sleep is associated with higher levels of a protein called CRP. C-Reactive Protein, this is a marker of inflammation and is a predictor of cardiovascular health.

Drifting off to sleep

A health indicator is the time it takes you to drift off to sleep – this is called your Sleep Onset Latency (S.O.L).

Thoughts are often active late at night and can lead to a prolonged S.O.L these will impact on your ability for a restful sleep.

If you are physically ready for sleep and have followed a suitable bedtime routine yet still struggle to sleep, your thoughts could be keeping you awake, these are referred to as;

Automatic Negative Thoughts ANTs. There’s no doubt we all have experienced these at some time, here’s some examples: -

“I can’t cope with this”

“I’m going to mess this up”

“This won’t work for me”

How do these thoughts stop us sleeping?

Why do we have these thoughts as we try to sleep?

  • Our brain is more idle so thoughts come more freely

  • Negativity bias can be a form of protection

  • The more we think we can’t sleep the less likely we are to achieve sleep

How to reduce A.N.T’s and shorten our S.O.L

  • Aim for positive thought retraining during the day

  • Keep a notebook by the bed – write down the ANT’s and schedule in ‘worry time’ nothing can be achieved in bed

  • Find a way to switch off your thoughts – a mindfulness or relaxation download often works

Nutritional Considerations

As with everything in nutrition there are foods that help and foods that hinder – a quick look at some foods that may prevent you getting a good sleep.

Sugary foods

  • Linked to poor sleep quality

  • Sleep deprivation activates the reward centre promoting cravings for more sugar and high fat foods

  • Long term sleep deprivation affects the body’s ability to regulate blood sugar



Affects people in different ways

Can delay your body’s body clock/circadian rhythm

Levels of caffeine after a drink peaks after an hour but remains for up to six hours


  • Reduces Sleep Onset Latency

  • Supresses REM sleep

  • Causes sleep disruptions

Foods that help

This list is much bigger! Think anything whole and natural and particularly avoid processed, high fat and high sugar foods. Some boosts naturally help to boost melatonin which helps us to relax

Melatonin Boosting Foods

  • Tomatoes

  • Cherries

  • Bananas

  • Kiwi fruits

  • Oats

  • Pineapples

  • Flaxseeds

  • Orange peppers

Other considerations

Being physically active can aid a restorative sleep and reduce your S.O.L. The obvious link is you’re more tired! Activity also reduces stress and anxiety which helps to body transition to a more relaxed state. Inactivity can lead to feeling wide awake when we should be sleepy!

Nutrition can help or hinder a good nights sleep. Some foods aid the natural production of Melatonin promoting relaxation and easing you into sleep, others try their best to keep you awake!

Bedtime Routines & Behaviours

Having a lifestyle that is in balance with our circadian rhythm will certainly help – this enables the body to enter its’ relaxed stage to get ready for the ‘sleep’ cycle and be physically and mentally prepared for sleep.

Supporting the Circadian Rhythm

Bedtime routine


Screen time

Nutritional influences

Caffeine and Alcohol

Room temperature

For more information on sleep and health particularly how food helps to balance our brain and emotions, which in turn helps us to get a good nights sleep please tune in to the sleep series in my brand new Podcast.

Check out the links to the Podcast Sleep Series here: -

Louise Mercieca

Nutritional Therapist

Personal Trainer

Early Years Nutrition Consultant

Award-winning Author

Food & Health Writer

Presenter on Early Years TV Food

Keynote speaker

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