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

Find out more

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.

5 benefits of a good night's sleep

  1. Sleep helps your mental health

    Sleep can help us recharge our batteries, to repair and re-energise. If we’ve had a stressful day then it’s a way to switch off and for our brains to process the information it’s received that day. When we’re asleep our brains actually rewire various neurones so that short-term memories become embedded into our long-term.

    A lack of sleep can cause an increase in negative thoughts, especially if it becomes a long-term problem.  Mental health charity Mind, say: “If you have little sleep you may feel less able to rationalise worries or irrational thoughts. It can also cause you to feel lonely or isolated, as if you feel tired you may not want to be sociable or see friends.”

  2. Keeps your heart healthy

    Sleep is essential for a healthy heart with The Sleep Foundation highlighting “…without long, deep periods of rest, certain chemicals are activated that keep the body from achieving extended periods in which heart rate and blood pressure are lowered. Over time, this can lead to higher blood pressure during the day and a greater chance of cardiovascular problems.”

    Studies into sleep have backed this up, with results showing consistently getting insufficient or poor sleep being linked with 7 out of the 15 leading causes of death; including cardiovascular disease, diabetes and hypertension.

  3. Boosts immunity and recovery from illness

    There is actually some science behind being told to rest up when you’re ill. Sleep releases proteins and infection-fighting antibodies to help combat inflammations and infections.

    This is also the case for any minor muscle injuries. As we sleep we’re generally using less energy, meaning what we would normally use during the day can instead be sent to restoring bones and muscles; through growth hormones which are produced during sleep.

  4. Helps us to function

    Sleep allows us to carry out executive functions, such as high-level decision making, flexible thinking and effective communication skills. In a sleep-deprived state our reaction time slows down, which can affect all of these.

    It can also help us maintain positive behaviours and carry out ethical practices whilst at work, for example.

  5. Stops snacking

    Sleep can help lower the levels of ghrelin, the hormone that tells us we’re hungry. It can also increase the levels of leptin which is the chemical that makes you feel full. So get some good quality sleep and you might be less tempted to repeatedly reach for those snacks during the day.

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 link 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.

How much sleep do we need?

In general, adults need between seven and nine hours of sleep but the exact amount varies from person to person.

The Sleep Foundation recommendations7, for newborns through to 65+ year olds are as follows:

  • Newborns (0-3 months): 14-17 hours each day
  • Infants (4-11 months): 12-15 hours
  • Toddlers (1-2 years): 11-14 hour
  • Preschoolers (3-5): 10-13 hours
  • School age children (6-13): 9-11 hours
  • Teenagers (14-17): 8-10 hours
  • Younger adults (18-25): 7-9 hours
  • Adults (26-64): 7-9 hours
  • Older adults (65+): 7-8 hours.

If you’re not getting enough of these hours on a regular basis, you’ll start racking up a sleep debt – hours owed to your body that will eventually catch up with you and cause slower reaction times and poor judgement, among other issues.

The good news is there are steps we can take to help us sleep better. And, should we need one, we all now have a great reason to have an early night, guilt-free!

woman sleeping on a bed

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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 more quickly, but the chances are your sleep quality will be affected by waking up multiple times during the night.

Sleep technology

Many of us have a general idea of what a sleep study involves – spending a night wired up to a machine while scientists monitor activity and run tests. However, according to Charlene Gamaldo, medical director of Johns Hopkins Center for Sleep at Howard County General Hospital, “the future of sleep research looks much different. Sleep clinical care and research is in a revolutionary place because of technology.” 

“…conducting sleep studies in a medical care centre is really going to be fading into the sunset or will be minimal at best. New approaches to testing are likely to take place in the comfort of your own home.”8

Global Market Insights predict that the sleep tech business is going to be a $27 billion industry by 2025.9 Some of the technologies on offer include:

  • Sleep trackers - Offering insights into your sleep stages and quality of sleep, sleep trackers can help provide clarity on what area needs to be improved in order to get a better night’s sleep. Ranging from wearables on your wrist to a device that fits on your mattress or under your pillow, the results can provide a steer for doctors.

  • Bedside monitors - Sitting on your bedside table, these monitors provide you with a sleep score but calculate it by using sonar waves to monitor your chest movement and breathing patterns. The results then feed into an overall sleep score. Also fed into this are stress levels and how much exercise has been done – both factors that can affect mental health.

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

Sleep tips for all ages - AXA PPP healthcare

Sleep apnoea and other disorders - 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.

7 The Sleep Foundation. How much sleep do we really need?

8 Charlene Gamaldo, Medical Director of Johns Hopkins Center for Sleep at Howard County General Hospital.The future of sleep studies.

9 Global Market Insights Sleep Tech Devices Market Growth Forecast Report 2019-2025. Published Date: October 2019. Report ID: GMI4405.

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