Lauren Davenport, Senior Physiologist at AXA Health

Health benefits of sleep


19 June 2023

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 help 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 physical health and mental wellbeing. 

Lauren Davenport, Senior Physiologist at AXA Health 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. It helps to protect our physical and mental wellbeing, enables us to utilise executive functions (like decision-making and problem-solving), and provides us with a sense of balance and consistency. 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 compared to your normal amount - 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.

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Why do we need to sleep?

There are various views on why we need sleep and what its function really 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 seems to be a universal core function, 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 very little 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 and connections, so that the important short-term memories become embedded into our long-term memory.

A lack of sleep can leave us feeling anxious or worried, cause an increase in negative thoughts, as well as cause us to make poorer health choices; 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 inflammation 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 well

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 and thinking time slows down, which can affect all of these.

As a collective, it can also help us maintain positive behaviours and carry out ethical practices whilst at work.

5. Stops snacking

Sleep can help control the levels of ghrelin, the hormone that makes us feel hungry. It can also decrease the levels of leptin, which makes you feel full. So, get some good quality sleep and you might be less tempted to repeatedly reach for those unhealthy snacks during the day. Remember though, everyone is different so cutting out certain foods may result in a decrease in your wellbeing; it’s worth seeking some advice if diet is a concern for you.

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 been increasing 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% increased 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, are as follows:

  • New-borns (0-3 months): needs vary widely. Can range from 11-19 hours
  • Infants (4-12 months): 12-16 hours
  • Toddlers (1-2 years): 11-14 hour
  • Pre-schoolers (3-5): 10-13 hours
  • School age children (6-12): 9-12 hours
  • Teenagers (13-18): 8-10 hours
  • Younger adults (18-25): 7-9 hours
  • Adults (18+): 7 hours or more

One caveat to remember, here. All of the studies and reports you might see in the news are based on sleep deprivation, not necessarily just poor-quality sleep.

If you are somebody who sleeps for 6 hours a night and have done so as long as you can remember, there’s likely little to worry about. 

If you’re not getting enough of sleep, relative to what you’d consider your ‘normal’, 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!

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. Don’t worry

It’s easy to panic when you read a scary headline about sleep deprivation. Many people resort to purchasing sleep trackers in an attempt to control their sleep a little better.

However, one of the best things you can do is to stop worrying so much about your sleep. Unless you are consistently struggling to get more than just a few hours of sleep, there’s plenty of simple things you can do to give your sleep a boost. Worrying about your sleep will only make things worse!

2. 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.

3. 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.

4. 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.

5. 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.

6. 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 bedtime.

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 Centre 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.

Try not to jump straight into investing in a sleep tracker before you’ve taken some time to self-reflect and work out your own cues. Your body is the best version of sleep technology you can get! It tells you when you are tired, when you should get to sleep, and lets you know what things might be helping or hindering your sleep.

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 

Eat your way to a better night’s sleep 

Ten top tips for a better night’s sleep 

Sleep tips for all ages 


  1. Insufficient Sleep Syndrome – NIH 
  2. Effect of One Week of Sleep Restriction on Testosterone Levels in Young Healthy Men – NIH 
  3. Britain’s Healthiest Workplace - RAND 
  4. Sleep Duration and All-Cause Mortality –NIH 
  5. The relationship of sleep duration and insomnia to risk of hypertension incidence: a meta-analysis of prospective cohort studies – NIH 
  6. Sleep Duration and Risk of Type 2 Diabetes: A Meta-analysis of Prospective Studies. Diabetes Care – NIH 
  7. How much sleep do we really need? – The Sleep Foundation
  8. The future of sleep studies – John Hopkins Medicine 
  9. Global Market Insights Sleep Tech Devices – Global Market Insights 

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