Dan Craig, Senior Physiologist at AXA PPP healthcare

Health benefits of sleep

27 May 2020

Dan Craig

Written by Dan Craig

Dan is a Physiologist with an MSc Exercise and Sports Sciences and is a Certified Nutrition Coach

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Few of us are at our best when we’ve had a bad night’s sleep. We might be irritable, sluggish or simply unable to focus on anything other than getting back to our beds. If it happens occasionally, there’s no reason to worry. An early night, or a lie in when work and other commitments allow, can restore us to our usual selves, with no real harm done. However, if we’re not getting enough good quality sleep on a regular basis, the long-term effects could be damaging to our health and mental wellbeing.

Daniel Craig, Senior Physiologist at AXA PPP healthcare explains why we need sleep, what can happen long term when we don’t get enough and what simple steps we can take in order to get a better night’s sleep.

How did you sleep last night?

Did you sleep well, with no interruptions? Do you feel refreshed? Or was your sleep disrupted? It may be that you woke up today feeling more tired than when you actually went to bed, a common problem for many of us. But is it something we just accept as part and parcel of our busy lives, or should we start paying more attention to how much, and how well we sleep?

Sleep is actually far more important than many of us give it credit for. We now know that when we experience a state of sleep deprivation a number of things can happen to our health and wellbeing, particularly in the long term. Studies have shown that consistently getting insufficient sleep - or experiencing poor sleep - over prolonged periods of time is linked with 7 out of the 15 leading causes of death, including cardiovascular disease, diabetes and hypertension.1

Other studies on the lack of sleep in men, show that after just one week of sleeping less than 5 hours a night there’s a 15% reduction in testosterone2 - equivalent to an ageing-effect of 10 years!

In short, if we want to stay well, we need to recognise the importance of sleep as a key component of a healthy lifestyle, in the same way we might our diet, fitness and our mental wellbeing.

Why do we need to sleep?

There are various views on why we need sleep and what its function is. You might say it’s to:

  • recharge our batteries
  • to repair or replenish our bodies
  • to re-energise ourselves.

All of these are true, but our more fundamental need for sleep is still heavily debated.

From an evolutionary perspective, there seem to be universal core functions, that we can’t carry out when we’re awake, despite the fact it leaves us in an unconscious, and therefore vulnerable state.

Yet there are a number of animal species that appear to require little or no sleep at all and can still function perfectly well – so what makes us different?

For now, questions around our inherent need for sleep remain unanswered, but we are aware of some of the benefits that sleep provides.

How does sleep benefit us?

It's protective – we need sleep for our physical and mental health and for our quality of life and safety. Sleep can help us rewire various neural connections in our brain, and helps us to process the information in our short-term memory that’s important to us and embed it into our long-term memory.

It supports executive functions – sleep allows us to carry out executive functions, such as high level decision making, flexible thinking and effective communication. In a sleep-deprived state, many of these functions could be compromised.

It moderates behaviours – sleep helps us maintain positive behaviours, for example avoiding unethical conduct or irritability that might impact our relationships at home, and perhaps more pertinently, at work!

Why is poor sleep a problem?

We’re beginning to unearth some fairly troubling information on what can happen when we’re living in a state of sleep deprivation.

From an economic perspective, lack of sleep is currently the second highest cause of loss of productivity in employees.3 This figure has significantly increased over the last 5 years from 28% in 2015 to 42% in 2019, representing a huge increase in people reporting having sleep problems.

On a more individual basis:

Adults who regularly sleep fewer than 6 hours per night have been shown to have a 12% increase in mortality risk.4

There’s a 25% relative increase in your blood pressure after a week’s worth of poor sleep (less than 6 hours a night).5 This is particularly worrying when you consider that high blood pressure is itself the biggest known cause of disability and premature death through stroke, heart attack and heart disease.

Type 2 diabetes becomes more of a risk if you’re sleeping under 7 hours a night, with there being a 9% increase risk per hour for every hour slept less than 7 hours. However, it’s worth noting there’s also an increased risk for sleeping more than 9 hours – the lowest risk therefore sits between 7-8 hours a night.6

Is there a risk between sleep and cancer?

You may have seen headlines about a potential link between sleep and cancer, but the answer is that we simply don’t know if this is the case. As we’ve seen, when our sleep is heavily disrupted on a regular basis, it may increase our risk of certain conditions, but when it comes to cancer, there are people still trying to work this out.

The good news is that we all now have a great reason to have an early night, guilt-free!

What can we do to get a good night’s sleep?

There are various tips we can try in order to give our bodies the best chance of a good night’s sleep.

  1. Routine

    Your body clock requires a steady routine, a sense of internal balance. Try to make sure that you’re waking up at the same time each day, ideally 7 days a week. Don’t worry about the time you go to bed, listen to your own cues and go to bed when you’re tired. That’s not to say you can’t allow yourself a bit of a lie in on the weekend but try to keep that consistency for the most part.

  2. Try to associate your bedroom with sleeping – and make it comfortable

    This might sound like an odd thing to say but how many of us have a TV in our bedrooms, or use our phones at night? For a better night’s sleep, try to reduce any distractions and make sure your bed is comfortable. Do you have a supportive mattress and a suitable pillow or pillows? These things can have a big influence on your sleep quality. Comfort is key.

  3. Make your room as dark as possible

    Try and make sure your room is as dark as possible and also nice and cool. The majority of us prefer a cooler room, as it brings our body temperature down and allows us to enter our sleep cycles more effectively. Blackout blinds and a fan by the bed in the spring/summer months can help us drop off and promote better quality sleep.

  4. Avoid clutter or working in the bedroom

    Try to maintain the boundaries between your work life and your home life. Ensure you have a dedicated workspace that’s away from the bedroom if possible, so your bedroom remains somewhere associated with relaxation and sleep, and declutter any mess on the floor around you. This has the effect of making your environment more calming.

  5. Staying hydrated (with the right liquid)

    Keeping hydrated can have an effect on your sleep cycle – if we’re dehydrated when we enter our sleep cycle we’re more likely to experience disturbed sleep. Make sure you drink enough water during the day and don’t be tempted to top up last thing at night, as that’s likely to result in you waking up in the night to go to the loo!

    Also be aware of drinking caffeinated drinks before bed. It takes around 9 hours to flush out your system, so having a coffee or tea before bed means it’s going to act as a stimulant at a time you want to be winding down. Ideally try and keep a caffeine-free window of at least 4-5 hours before bed time.

    Alcohol before bed might help you fall asleep quicker but the chances are your sleep quality will be affected by waking up multiple times during the night.

Next steps

If you’re having real trouble sleeping and you feel like this has become an issue that doesn’t seem to be improving, it’s worth having a chat with your GP. There’s plenty of help available for sleep disorders, as well as online resources such as NHS Live Well, National Sleep Foundation and Mind.

Further resources

Sleep hub – AXA PPPP healthcare
Eat your way to a better night’s sleep – AXA PPP healthcare
Ten top tips for a better night’s sleep - AXA PPP healthcare


1 Chattu et al. (2018) Insufficient Sleep Syndrome: Is it time to classify it as a major noncommunicable disease? Sleep Science, 11(2): 56-64.

2 Leprault, R & Cauter, E.V. (2011) Effect of One Week of Sleep Restriction on Testosterone Levels in Young Healthy Men. JAMA, 1:305(2): 2173-2174.

3 Britain’s Healthiest Workplace, RAND Europe Corp (2019). Reported figures based on 450 employers, >158,000 employees in the UK.

4 Cappuccio, F. P., et al. (2010) Sleep Duration and All-Cause Mortality: A Systematic Review and Meta-Analysis of Prospective Studies. Sleep. 33(5): 585–592.

5 Meng L. et al., (2013) The relationship of sleep duration and insomnia to risk of hypertension incidence: a meta-analysis of prospective cohort studies. Hyp Res, 36: 985-995.

6 Shan Z. et al., (2015) Sleep Duration and Risk of Type 2 Diabetes: A Meta-analysis of Prospective Studies. Diabetes Care, 38(3): 529-537.