Sleep is a biological necessity. It is not optional. For our bodies to survive we need to sleep. And it is equally as important for our brains to get a good night’s sleep. Both our physical and mental health depends on it.
As sleep scientist Dr Allan Rechtschaffen said: “If sleep does not serve an absolutely vital function, then it is the biggest mistake the evolutionary process has ever made.”
So, why is sleep so necessary?
Sleep is necessary for our health and wellbeing. Sleep enables the body to recover and rejuvenate, to grow muscle, repair tissue, and synthesize hormones. The brain needs sleep to help us solidify and consolidate memories by processing and storing all the information we take in each day.
The benefits of sleep include:
- Increased recovery
- Lower blood pressure
- Decreased risk of cardiovascular disease
- Decreased risk of diabetes
- Increased immunity
- Reduced stress
- Weight maintenance/ aids weight loss
- Improved memory
- Improved mood
- Increased attention and focus
For our immune system to function properly we need adequate, good quality sleep. We have natural ‘killer cells’ within our bodies which identify anything malignant, and these killer cells decrease with lack of sleep. This in turn decreases our body’s ability to fight off disease and to repair.
Studies have shown that restricted sleep of only four hours results in a 70 per cent drop in natural killer cells, creating immune deficiency. As immunity decreases, chances of tumours, chronic inflammation and cardiovascular disease increase. Basically the less you sleep, the higher your chances of mortality.
As world renowned sleep expert Matthew Walker puts it so succinctly in his Sleep is your Superpower TED talk : “The shorter your sleep, the shorter your life.”
Matt Walker is a Professor of Neuroscience and Psychology and Director of the Sleep and Neuroimaging Laboratory at the University of California, Berkeley and has spent the past twenty years researching sleep. He has published over 100 scientific research studies during the course of his career and in his recent internationally best-selling book Why We Sleep he talks in detail about the reasons we need to sleep.
He says: “We sleep for a rich litany of functions, plural – an abundant constellation of nighttime benefits that service both our brains and our bodies. There does not seem to be one major organ within the body, or process within the brain, that isn’t optimally enhanced by sleep (and detrimentally impaired when we don’t get enough). That we receive such a bounty of health benefits each night should not be surprising. After all, we are awake for two-thirds of our lives, and we don’t just achieve one useful thing during that stretch of time. We accomplish myriad undertakings that promote our own well-being and survival. Why, then, would we expect sleep – and the twenty five to thirty years on average, it takes from our lives – to offer one function only?”
While a balanced diet and exercise are of vital importance for our overall health, it is now becoming recognised that sleep is equally as important, if not the absolute pinnacle of this holy trinity.
If you think about it, the physical and mental consequences caused by even one night of poor or inadequate sleep is immense compared to those caused by the equivalent absence of food or exercise.
There is now an abundance of new scientific research out there showing that sleep is necessary for just about every function of the body and the question is no longer, what is sleep good for but are there any biological functions that do not benefit from a good night’s sleep?
The answer seems to be a resounding no, there are no biological functions that do not benefit from good sleep.
What is considered to be a ‘good’ amount of sleep for humans?
Everybody has a unique sleep requirement depending on genetic and physiological factors, as well as age, sex and previous sleep amounts. However, a simple definition of sufficient sleep is an amount that is followed by spontaneous awakening and the feeling of being refreshed and alert for the day.
On average, most healthy adults need between seven to nine hours of sleep per night to function at their best. Children and teens need more, and despite the notion that our sleep needs decrease with age, most older people still need at least seven hours of sleep. It is not uncommon for older adults to experience trouble sleeping for this many hours at night so daytime naps can help fill in the gap.
It is worth noting that there is a big difference between the amount of sleep you need to function optimally and the amount you can get by on.
A 2018 Sleep Survey by Chemist 4U showed that the average person living in the UK sleeps for between 5.78 and 6.83 hours per night. That’s a lot less than the recommended eight hours! In today’s fast-paced society six or so hours of sleep may sound pretty good but in reality it’s a recipe for chronic sleep deprivation.
And it’s not just the number of hours you spend asleep that’s important but the quality of the sleep. If you achieve eight hours of sleep but still have trouble waking up in the morning or staying alert all day, you may not be spending enough time in the different stages of sleep.
Stages of sleep
- Stage 1 – light sleep (you can be easily woken).
- Stage 2 – your heart rate and body temperature start to decrease, eye movement stops and brain waves slow down.
- Stage 3 – deep sleep – your brain produces slow brain waves with occasional faster waves (this is the stage where sleep talking, walking and night terrors can occur).
- Stage 4 – deep sleep – your brain produces slow brain waves almost exclusively.
- Stage 5 – REM phase – rapid eye movement occurs and brain waves are similar to those at waking state. This is the stage when dreams occur and we are paralysed.
While each stage of the sleep cycle offers different benefits, deep sleep and mood-boosting REM sleep are particularly important. During stages three and four the most restorative benefits of sleep occur. Human growth hormone is released and the immune system is restored.
What is sleep deprivation?
If you regularly get less than eight hours of sleep each night, the chances are you’re sleep deprived. What’s more, you probably have no idea just how much lack of sleep is affecting you. If you’ve made a habit of skimping on sleep you may not actually remember what it feels like to be truly wide-awake and fully alert.
Signs that you’re not getting enough sleep include:
- Needing an alarm clock in order to wake up on time
- Hitting the snooze button
- Struggling to get out of bed in the morning
- Feeling tired or sluggish in the afternoon
- Getting sleepy in meetings or warm rooms
- Feeling drowsy after heavy meals
- Feeling drowsy when driving
- Needing a nap to get through the day
- Falling asleep while watching TV or relaxing in the evening
- Feeling the need to sleep in at the weekends
- Falling asleep within five minutes of going to bed
The effects of sleep deprivation
Sleep deprivation has a wide range of negative effects on the body and the brain that go way beyond daytime drowsiness. Lack of sleep affects your immune system, mood, judgement, coordination and reaction times. In fact, in the short term, sleep deprivation can affect you in ways similar to being drunk.
- Fatigue, lethargy, and lack of motivation
- Low mood and irritability
- Increased risk of depression
- Decreased sex drive
- Impaired learning ability and concentration
- Memory problems
- Reduced creativity
- Reduced problem-solving skills and difficulty making decisions
- Inability to cope with stress
- Difficulty managing emotions
- Premature skin aging
- Weight gain
- Weakened immune system – leading to frequent colds and infections
- Impaired motor skills and increased risk of accidents
- Hallucinations and delirium
- Increased risk of serious health problems including stroke, diabetes, high blood pressure, heart disease, Alzheimer’s disease, and certain cancers
As well as the potentially life-threatening conditions that can be caused or exacerbated by a lack of adequate sleep, sleep deprivation has a direct link to overeating and weight gain. This is mainly because when you’re short on sleep your body craves sugary foods to give you a quick energy boost.
So, despite your best efforts to lose weight through exercise and the right nutrition, if you are getting less than a good night’s sleep this could be seriously affecting your chances of achieving the results you want.
There are two hormones in the body that regulate feelings of hunger and fullness. The colloquially named ‘hunger hormone’ ghrelin stimulates appetite, while the ‘satiety’ hormone leptin sends signals to the brain when you are full. When you don’t get enough sleep ghrelin levels go up, stimulating your appetite so you want more food than usual, while leptin levels go down, meaning you don’t feel full or satisfied.
In a nutshell, the less sleep you get, the more food your body will crave, and probably the wrong kinds of food as well.
In his book Why We Sleep Matthew Walker discusses a number of studies on sleep and appetite regulation by his colleague Dr Eve Van Cauter PhD, director of the Sleep, Metabolism and Health Center (SMAHC) in the Department of Medicine at the University of Chicago.
In one study Dr Van Cauter recruited a group of young healthy adults, who were given 8.5 hours of sleep for five nights. Then, the same group was only allowed 4-5 hrs of sleep a night for five nights. They were provided with exactly the same type and amount of food and their levels of physical activity were kept constant.
Each day the participants sense of hunger and food intake were monitored, along with their circulating levels of ghrelin and leptin. Van Cauter discovered that: “Individuals were far more ravenous when sleeping four or five hours a night. This despite being given the same amount of food and being similarly active, which kept the hunger levels of the same individuals under calm control when they were getting eight or more hours of sleep.”
Basically, the study showed that poor sleep decreased leptin and increased ghrelin. As Matthew Walker explains: “From a metabolic perspective, the sleep-restricted participants had lost their hunger control. By muting the chemical message that says “stop eating” (leptin), yet increasing the hormonal group that shouts “please keep eating” (ghrelin), your appetite remains unsatisfied when your sleep is anything less than plentiful, even after a kingly meal.”
Studies have also shown that not only do we consume more when sleep deprived but psychological distress can lead to a preference for energy dense foods to upgrade energy levels and alleviate negative mood. Our self-control is also lowered making it harder to resist temptation.
How to get the sleep you need
After all this talk of the potentially devastating effects of sleep deprivation, how on earth do we get the sleep we actually need?
If you’re experiencing sleep issues, firstly, rule out any medical causes as a sleep disturbance may be a symptom of a physical or mental health issue, or a side-effect of certain medications.
- Regular sleep schedule
Try to stick to a regular sleep schedule, going to bed at the same time each night and getting up at the same time every day, including weekends. It can be hard for the body to adjust to changes in sleep patterns, and sleeping later at the weekends doesn’t make up for poor sleep during the week!
- Avoid caffeine
Try to avoid caffeine and sugary foods later in the day as these can disrupt sleep. Coffee, tea, Coke and chocolate all contain caffeine, which is a stimulant. Even consuming these in the afternoon can affect your sleep but definitely avoid them in the evenings just before bedtime.
- Avoid alcohol
Avoid alcohol late at night. Alcohol in your system can reduce your REM sleep and keep you in the lighter stages of sleep. Drinking too many fluids late in the day can cause frequent awakenings to go to the loo.
- Regular Exercise
Make sure you exercise regularly, aiming for at least 30 minutes or more every day, but try to exercise no later than two to three hours before bed. While exercise can greatly improve the symptoms of many sleep disorders and problems, if you exercise too close to bedtime there may be higher amounts of cortisol or adrenaline in your body which can inhibit sleep.
- Relaxing bedtime routine
Develop a relaxing bedtime routine. Avoid screens, work, and stressful conversations late at night. Instead, wind down and calm your mind by taking a warm bath, reading by a dim light, or practicing a relaxation technique to prepare for sleep.
- Good sleep environment
Improve your sleep environment. Keep your bedroom dark, quiet, cool and screen-free. We sleep better at night if the temperature is on the cool side and the room is dark. Gadgets such as mobile phones and computers can be a distraction, and the light they emit suppresses the secretion of melatonin, a hormone that regulates sleep/ wake cycles.
- Postpone worrying
If you wake during the night feeling anxious about something, make a brief note of it on paper and postpone worrying about it until the next day when it will be easier to resolve.
Improving the overall quality of your sleep will boost your mental and physical health, and the overall quality of your life, including your productivity, emotional balance, creativity, vitality, and even your weight.
I work shifts, I just can’t get enough good sleep
There are times and circumstances when we simply can’t get a regular eight hours a night. If you’re a shift worker – for example a pilot, flight attendant, fire fighter, factory worker, nurse, paramedic or police officer – you’re probably used to irregular sleep patterns and daytime sleeping but sometimes people who work shifts have some difficulty when it comes time to sleep.
This is because our brains and our bodies are not really designed to switch back and forth between day sleep and night sleep. Our bodies are influenced by our circadian rhythms, which are basically our body’s internal clock that tells us when to be awake and when to sleep. These rhythms are controlled by a part of the brain that is influenced by light, hence sunlight encourages us to wake up.
However there are things you can do to help you switch to daytime sleeping when required, such as trying to mimic a nighttime environment in your bedroom by making it as dark as possible – use blackout blinds or wear an eye mask. Being exposed to bright light when you start your “day” (at whatever time this might be) can help train your body’s internal clock to adjust.
Also, keep your bedroom cool (houses tend to be warmer during the day than the night), and try to get into a regular pattern of sleep with longer night shifts and longer rest periods in between, if possible.
Ultimately, try to transition away from working night shift patterns! In the meantime, these tips should help you sleep well:
- Limit night shifts
Try not to work lots of night shifts in a row – you may become increasingly more sleep-deprived over several nights of working. If you can limit night shifts and schedule days off in between it will give your body time to recover.
- Avoid frequently rotating shifts
A regular pattern of shifts is better so that your body knows what’s coming. If you can’t avoid rotating shifts, it’s easier to adjust to a schedule that rotates from day shift to evening to night rather than the reverse order.
- Avoid long commutes
Avoid long journeys to and from work that take time away from sleeping – maximise the time you have to unwind and relax before attempting sleep.
- Keep your workplace brightly lit
Bright light promotes alertness during waking times. If you’re working a night shift, expose yourself to bright light, such as that from special light boxes and lamps designed for people with circadian-related sleep problems, when you wake up. Then keep your place of work brightly lit.
- Limit caffeine intake
Drinking a cup of coffee or tea at the beginning of your shift may help promote alertness but don’t consume caffeine near the end of your shift or you may have trouble falling asleep when you get home.
- Avoid alcohol
Avoid alcohol before you are due to sleep. As we mentioned previously, alcohol can reduce your REM sleep and keep you in the lighter stages of sleep. For some people a heavy meal before bed can also cause digestive issues that interfere with sleep, although some people find that eating before bed actually helps sleep. The key is to get to know your own body.
Take regular exercise but try to avoid it just before you want to sleep. Exercise can help to improve sleep quality, as it increases time spent in deep sleep – the most physically restorative sleep phase. Deep sleep helps to boost immune function, support cardiac health, and control stress and anxiety.
- Keep your room dark and cool.
If you’re trying to sleep during the day, making your bedroom as dark as possible will help to trick your brain into thinking it’s nighttime, which helps those circadian rhythms again. Cooler temperatures are more optimum for sleep during the day or night.
- Keep the noise down
Keep your bedroom quiet and make sure no-one else in your household wakes you with loud noises. Ask your family to limit phone calls, visitors, and the use of vacuum cleaners and so on, during your sleep hours.
- Avoid bright light
Avoid bright light on the way home from work if possible and limit screen-time just prior to sleep time. The light emitted from TVs, laptops, tablets and smart phones suppresses the release of the sleep-inducing hormone melatonin, and makes it more difficult to fall asleep.
How to maximise health when you’re getting sub-optimal sleep
If you have no problem sleeping when you get the opportunity but can’t get a solid eight hours due to shift patterns, a busy schedule or other circumstances, such as having young children, there are other things you can do to help you stay healthy.
Unfortunately, you can’t make up for lost sleep or accumulate sleep deprivation through the week and wipe the slate clean at the weekend with a mammoth lie-in, however paying back ‘sleep-debt’ is always a good idea if you’ve missed sleep. You will feel a whole lot better mentally and physically if you can get a good chunk of quality sleep after a period of sleep deprivation.
The best sleep habits are, of course, consistent routines, much like healthy eating and exercise routines, but if it is simply not possible to make changes in your lifestyle to achieve this, the following tips may help you to maintain your physical health and keep on top of life’s everyday challenges:
- Daytime naps
If you aren’t getting enough sleep at night, take naps during the day if you can fit them in. For example, if you’ve been awake in the night feeding your baby, try to take a nap when the baby sleeps during the day. Even a ten minute nap can help you to feel more energised and increase your productivity.
- Eat healthily
As we explained earlier, feeling tired can often lead to eating more and making poor food choices due to the increase in the hunger hormone ghrelin and the drop in the satiety hormone leptin. Feeling tired or sleepy can result in the desire for sugary snacks or caffeinated drinks for a quick energy boost. The problem is that ‘sugar highs’ only last a short time and lead to energy crashes, followed by the desire for another quick energy boost.
We tend to make poor food choices when we’re sleep deprived as a lack of sleep disrupts brain activity, which can lead to inhibitions in good decision-making. Studies have shown that sleep-deprived individuals preferred high-calorie foods compared to when they were well-rested.
So, as easy as it is to reach for a calorie-laden sugary snack for a quick energy boost, try instead to think about healthy choices. Stock up on healthy foods and make sure you take something with you to work if you know you will experience an energy slump at a certain point in the day.
Some easy energy-boosting snack ideas include:
*An apple with a protein bar or shake – the protein from the bar or shake will give you long-lasting energy and your body will use the apple’s natural sugars more slowly than it would the processed sugars found in a chocolate bar or a doughnut.
*Yoghurt and cereal – Fat-free Greek yoghurt with a whole grain cereal sprinkled on top will give you a good carb-protein combination to boost your energy and keep you feeling fuller for longer.
*Popcorn – air-popped, unflavoured popcorn is mostly made up of carbohydrate. It’s low in fat and high in fibre, making it a good snack option in comparison to crisps. Just make sure you don’t choose a flavour covered in butter and salt! There are lots of ‘healthy’ options available in most supermarkets now.
*Hard-boiled eggs – an egg is a great combination of proteins and fats. Hard-boiling eggs is a convenient way to take them with you to work or when you’re out and about.
*Dark chocolate – a square of dark chocolate is loaded with theobromine, a chemical compound that’s similar to caffeine. It’s the perfect afternoon pick me up if you’re in need of a treat!
- Get active
Exercise can aid sleep but it also contributes to general health and wellbeing regardless of sleep patterns.
Regular exercise can reduce your risk of developing many long-term (chronic) conditions, such as heart disease, type 2 diabetes, stroke, and some cancers. Research also shows that physical activity can boost self-esteem, mood, and energy, as well as reducing your risk of stress, depression, dementia and Alzheimer’s disease.
- Be strict with yourself
Set yourself a bedtime and stick to it. The earlier you get to bed and the more sleep you get, the more refreshed you will feel when you wake, and the more able to cope with the day’s challenges. Your chores and workload will still be there tomorrow but after adequate sleep you will be far more productive.
If you stay up late because you feel overwhelmed by how much you have to do, you may oversleep the next day because you are tired. You will then feel even more stressed because you have less time during the day, and end up staying up late again, creating a vicious cycle.
If you oversleep in the morning you might also miss out on eating a healthy nutritious breakfast that will give you much-needed energy to see you through the morning. This could lead to snacking and a higher caffeine intake.
A poor sleep cycle of unhealthy behaviours can ultimately transpire into poor lifelong habits, which affect your long-term health and mental wellbeing.
It is important to stop and take stock, think about what is best for your health as well as your productivity levels. Being strict with yourself means making smart choices and prioritising tasks, including sleep.
In order to break unhealthy sleep cycles you sometimes need to dig deep to find the discipline required to get back on track. Make a sleep schedule for yourself and stick to it.
Matthew Walker eloquently sums up the importance of sleep in Why We Sleep: “Within the brain, sleep enriches a diversity of functions, including our ability to learn, memorize, and make logical decisions and choices. Benevolently servicing our psychological health, sleep recalibrates our emotional brain circuits, allowing us to navigate next-day social and psychological challenges with cool-headed composure.
“Downstairs in the body, sleep restocks the armory of our immune system, helping fight malignancy, preventing infection, and warding off all manner of sickness. Sleep reforms the body’s metabolic state by fine-tuning the balance of insulin and circulating glucose. Sleep further regulates our appetite, helping control body weight through healthy food selection rather than rash impulsivity. Plentiful sleep maintains a flourishing microbiome within your gut from which we know so much of our nutritional health begins. Adequate sleep is intimately tied to the fitness of our cardiovascular system, lowering blood pressure while keeping our hearts in fine condition.”
Sleep isn’t merely a time when your body shuts down. It is a time when your body rejuvenates and repairs while your brain processes the information overload from the day.
During deep sleep your body works to repair muscle, organs, and other cells. Chemicals that strengthen your immune system circulate in your blood and the body releases hormones to slow breathing and relax muscles in the body, helping the process that reduces inflammation and assists with healing.
While you sleep, your brain clears away toxins, processes information, forms new memories and consolidates older ones.
Without enough hours of restorative sleep, productivity, learning and creativity all suffer. If you regularly skimp on sleep you could be headed for ill health, both physically and mentally.
When you’re struggling to meet the demands of a hectic schedule or just finding it hard to sleep at night, surviving on less hours may seem like a good solution but even minimal sleep loss can take a substantial toll on your mood, energy, judgement, and ability to handle stress. In the long-term, chronic sleep loss can wreak havoc on your wellbeing.
It has been scientifically proven that good sleep is as important to humans as good nutrition and exercise. Without it we simply cannot function and it is up to us to make every effort to get the very best sleep we can in our own individual circumstances.
Quick Myths and Facts about Sleep!
Myth: Getting one hour less sleep per night won’t affect your daytime functioning.
Fact: Losing even one hour of sleep can affect your ability to think properly and respond quickly. It also compromises your cardiovascular health, energy balance, and ability to fight infections.
Myth: Your body adjusts quickly to different sleep schedules.
Fact: Most people can reset their biological clock (circadian rhythm) but only by one or two hours per day at best. Consequently, it can take more than a week to adjust after traveling across several time zones or switching from a day to a night shift.
Myth: Extra sleep can cure excessive daytime fatigue.
Fact: While the quantity of sleep you get is important, it’s the quality of your sleep that is really important. Some people sleep eight or nine hours a night but don’t feel well rested when they wake up because the quality of their sleep is poor.
Myth: You can make up for lost sleep during the week by sleeping more at the weekends.
Fact: Although this kind of sleeping pattern will help partly relieve a sleep debt, it will not completely make up for the lack of sleep. Furthermore, sleeping later at the weekend can affect your sleep-wake cycle, making it harder to go to sleep at the right time on Sunday night and get up early on Monday morning.