We all know how it feels to get a lousy night’s sleep. You feel groggy in the morning, yawn all day long and can’t seem to “get going.” When this happens, we tend to get through the day on a combination of caffeine and sheer willpower.
Everyone has an off-night every now and then, for whatever reason. But for many people, including those with young children or demanding jobs, a lack of sleep is not a one-off. Some people regularly find themselves running on only a few hours’ sleep, or less. No matter our situation, we’re all guilty of failing to prioritize our sleep from time to time.
But what, exactly, counts as “enough” sleep? How does not getting enough sleep affect our minds and bodies? And how important is a good night’s sleep for a healthy and happy life? Today, we’ll explore this question.
How Much Sleep Do We Need?
Scientists have conducted many sleep studies and questionnaires to discover the effects of specific amounts of sleep. The most recent in-depth research was published in 2015 by the National Sleep Foundation.
It defined the recommended amount of sleep for several different age categories:
The amount of necessary sleep varies widely with age. Generally speaking, the younger the child, the more sleep they’ll need. Newborns, on average, require 14 to 17 hours of sleep per 24-hour period.
The amount of sleep slowly reduces as children age. Toddlers need between 11 – 14 hours per night, whereas school-aged children need 9 to 11 hours. Once they become teenagers, 8 to 10 hours is more appropriate.
For adults (18 – 64 years old), the recommended sleep per night is between 7 to 9 hours. However, everyone is different.
The research suggests that for some people, 6 hours or even 10 hours may be appropriate. For the vast majority, though, an average of 8 hours is considered a good night’s rest.
As you get older, your need for sleep slightly decreases. Over 65s need roughly 7 to 8 hours per night, though, for some, as little as 5 to 6 could be acceptable. It isn’t known exactly why this is the case.
Everyone’s needs are different. The above guidelines are only a “rule of thumb.” How much sleep you need may vary. If you feel well-rested in the morning, and healthy and alert throughout the day, you’re probably getting enough.
If you feel exhausted when you wake up and tired during the day, you likely need more.
What Are the Benefits of Sleeping Early vs. Sleeping Late?
So, now you know how much sleep you should be getting each night. But does it make a difference when you sleep? You may have heard the old saying: early to bed and early to rise makes a man healthy, wealthy, and wise. But if you get your 8 hours, does it matter whether bedtime is at 10 pm or 3 am?
Whether you go to bed early or late depends on your circadian rhythm, or “biological clock.” It’s an inbuilt 24-hour cycle of sleepiness and wakefulness, governed by our hypothalamus. The circadian rhythm decides when we feel sleepy and alert at different points in the day.
Not everyone’s circadian rhythm is the same. According to the International Journal of Chronobiology, there are three main “chronotypes”:
- Morning Larks get up between 5 am – 7:45 am, and go to bed between 8 pm – 10:15 pm.
- Night Owls get up between 9:45 am – 12 noon, and go to bed between 12:30 am – 3 am.
- Intermediate types get up between 7:45 am – 9:45 am and go to bed between 10:15 pm – 12:30 am.
A recent study in Chronobiology International found night owls have a higher chance of developing certain health problems, including:
- Neurological disorders
- Gastrointestinal disorders
- Respiratory disorders
- Mental illness
- Risk of mortality
This was after factoring in sleep duration, and other lifestyle characteristics. So, even if you get the right amount of sleep, a late bedtime could be damaging to your health. It isn’t clear exactly why, though the importance of sleep quality is an essential factor to consider. Sleeping at unconventional times could mean your sleep is disturbed more frequently, due to daylight and noise from neighbors.
Why is Sleep Important for the Brain?
So, now we’ve covered what constitutes healthy sleep. But why, exactly, is sleep so crucial to a healthy life?
There are many reasons why sleep is important, for both the brain and the body. First of all, let’s look at the brain. There are four main ways in which sleep plays a vital role in keeping the mind healthy.
You may have noticed that when you’re tired, you seem to be more forgetful. This isn’t a simple coincidence. A study in Physiological Reviews found that getting enough sleep is key to a healthy memory.
While you sleep, your brain is hard at work. It sorts and consolidates all of your experiences from the day before. It filters out everything that you won’t need to remember, such as what color socks you were wearing. Vital facts and experiences are stored so that you can recall them at a later date. Not getting enough sleep can be incredibly damaging to this process. You may forget where you put an item the day before or omit important information that you learned recently.
Short-term memory is also affected by poor sleep. For example, you might fail to recall something that was said to you only minutes ago. Or, you may frequently forget what you’re doing when you walk into a room.
2) Cognitive Performance
Cognitive performance refers to your ability to learn, understand, think, and make decisions. According to research in the Journal of Neuropsychiatric Disease and Treatment, sleep is crucial for almost every aspect of cognition.
These include, among others:
- Decision making
- Logical reasoning
- Language ability
- Executive functions such as planning, organizing and time management
Without enough sleep, you’ll find that almost every aspect of day-to-day mental functioning becomes difficult. You may struggle to pay attention at school or work. You’ll find it hard to understand things that would otherwise be straightforward. You may make seemingly careless mistakes, or struggle to concentrate on things.
This is all due to how sleep helps to maintain the brain’s health. While you sleep, specific areas of your brain are allowed to rest and “reset.” If you’re sleep-deprived, these structures – such as the prefrontal cortex – can’t function properly.
Along with your mental functions, can lack of sleep affect your mood? According to research by Tel Aviv University, the answer is yes. If you’ve ever felt miserable or short-tempered when you’re tired, now you know why.
Like cognitive functions, emotions are produced in the brain. Specifically, the part of the brain responsible for emotions is the limbic system. Because sleep promotes the health and functioning of brain structures, sleep is also the key to emotional regulation. A healthy limbic system allows you to react appropriately to things, and experience the right emotions at the right times.
If you don’t get enough sleep, your limbic system won’t work as well as it should. This could cause you to:
- Under or overreact to emotion-invoking stimuli
- Experience negative emotions, such as sadness and anger, for seemingly no reason
- Dwell on negative experiences for longer than usual
- Become stressed easily, leading to anxiety and worry
Experiencing excessive negative emotions can be highly detrimental to your mental health. Not only that, but it can also cause you to lose even more sleep. This results in a vicious cycle which may be hard to break.
Another critical function of the brain is creativity. This trait allows us to think up novel ideas. It helps us to form new thoughts and connect ideas together. Without creativity, it would be hard to think of solutions to problems or progress in our careers.
Sleep plays a significant role in fostering creativity. According to a study by the University of California, REM (rapid eye movement) sleep is responsible. This is a stage of sleep in which dreams are produced. In their study, the researchers found that participants who did not get REM sleep found it harder to solve problems creatively.
REM sleep tends to occur after you’ve been asleep for at least 90 minutes. Therefore, if your sleep is frequently disturbed, you may not be getting enough REM sleep. This can lead to the deterioration of your creativity levels.
What Happens to Your Body When You Don’t Get Enough Sleep?
We’ve now covered the main ways in which your brain benefits from getting enough sleep. But what about the rest of you? It’s not just your mind that becomes healthier when you rest well. Your body feels the benefits, too.
When you’re sleep deprived, your body suffers repercussions from it. A lack of sleep affects your body in the following ways.
1) Weight Gain
Are you struggling to lose weight, or to remain at a healthy weight for your height? If so, your sleep habits could be partially responsible.
A study in the American Journal of Epidemiology found a strong association between sleep and weight gain. People who regularly sleep fewer than 7 hours a night have a higher risk of becoming obese. This is a long-term association; so, one night of poor sleep won’t make you suddenly gain a pound. However, if you’re regularly sleep deprived, you’ll put on more weight over the years than you would otherwise.
There are three possible reasons why a lack of sleep causes weight gain. Firstly, feeling tired during the day means you’ll be less likely to engage in physical exercise. Secondly, suffering from a lack of sleep can encourage your body to overproduce a hormone called ghrelin. Ghrelin increases your appetite, which results in more food intake and therefore weight gain.
It’s also thought that sleep can interfere with your metabolism. People who are sleep deprived are more likely to gain weight, regardless of caloric intake and output. So, even if you eat correctly and exercise, you still need to sleep well to stay healthy.
2) Weaker Immune System
According to WebMD, getting inadequate sleep is likely to result in you becoming sick. This is because disrupted sleep can compromise your immune system. So, if you frequently find yourself battling colds and infections, you may have your sleeping habits to blame.
If you become exposed to a virus or bacteria during your day-to-day life, your immune system tries to fight it off. To do this, it uses proteins called antibodies, and protective white blood cells known as T-cells. These helpful illness-fighting agents are produced while you sleep. With a properly functioning immune system, you should be generally healthy and resistant to infection.
If you don’t get enough sleep, however, your immune system can become compromised. Your body won’t be able to produce enough antibodies and T-cells to keep you protected. With that, you’ll be more at risk of catching colds, flu, and other infectious illnesses. You’ll also feel sicker than someone with a healthy immune system. Not to mention, it will take you longer to recover than it would otherwise. Getting proper sleep ensures your body stays as healthy as it can.
3) Lower Libido
Your sexual health can also suffer due to sleep deprivation. Not getting enough sleep can result in a decreased libido (sex drive). So, if your intimate relationships are suffering, it’s time to look at your sleep habits.
For men, low libido is one of the main symptoms of testosterone deficiency. And of course, a good night’s sleep is key to maintaining testosterone levels. A sleep study was conducted by the University of Chicago. They found that sleeping for five hours or less per night can reduce testosterone in men by 15%. This dip in testosterone can occur after just one week of sleep deprivation.
In women, a study in the Journal of Sexual Medicine found that women who sleep more have a greater desire for sex. After a good night’s sleep, women are more likely to have sex with their partner the following day. They also report higher levels of arousal during the day than women who are sleep-deprived.
All in all, whether you’re male or female, good sleep habits are crucial for a healthy sexual relationship.
This may seem obvious, but it’s an important point to mention. A lack of sleep is likely to make you feel drowsy during the day. You may find yourself daydreaming or falling asleep at inappropriate times. Drowsiness also causes inattentiveness, a slow reaction time, and poor decision-making.
Daytime drowsiness can pose a serious problem. It can make it harder to carry out tasks that would usually be simple, like housework and errands. You might also find yourself in trouble with your boss if you drift off while at work.
Not only that, but drowsiness can also make it unsafe to get behind the wheel. Driving while you’re tired is very similar to driving under the influence of alcohol. According to the CDC, drowsy driving can cause up to 6,000 fatal car crashes each year in the USA.
Even if you don’t drive, you’re more likely to get into other kinds of accidents while sleep deprived. Improving your sleep habits could save your life.
5) Poor Skin
Is there any truth to the term “beauty sleep”? According to Aesthetics Journal, there is. Good sleep is vital for keeping your skin looking and feeling healthy.
Your skin can worsen due to a lack of sleep in the following ways:
- Increased lines (wrinkles)
- Dark circles under the eyes
- Reduced elasticity and sagging
- Uneven pigmentation (dark spots)
- Dull complexion
- Acne breakouts
- More visible pores
This is because sleep deprivation causes stress on the body. When your body is stressed, it releases a hormone called cortisol. Cortisol has many adverse effects on the body, one of which being the damage it causes to facial tissue. It can change your skin’s pH level, and reduce collagen production.
As you sleep, the skin also repairs itself and recovers moisture lost during the day. If you don’t get enough sleep, it can’t self-heal as effectively. This may result in your skin appearing dehydrated and dull. You’ll also recover more slowly from damage such as sunburn.
6) Reduced Muscle Growth
If you’re the type of person who works out, you may be wondering: how important is sleep to building muscle?
When you exercise, you create microscopic tears in the cells of your muscles. To repair these tears, your body adds more muscle tissue to them. This results in your muscles become larger over time.
However, this restorative healing primarily occurs while you’re sleeping. As you sleep, your body produces growth hormone which helps your muscles to repair themselves. If you don’t get enough sleep, this process will be inhibited.
If you are sleep deprived, your body also releases cortisol, the stress hormone. The presence of cortisol in the body encourages your muscle tissues to break down.
The combined result of these two processes means that a lack of sleep results in reduced muscle growth. If you don’t sleep enough, you won’t gain as much muscle as someone who gets 8 hours.
7) Increased Risk of Disease
We’ve already looked at how a lack of sleep can compromise your immune system. However, it’s not just colds and flu that you have to worry about. Suffering from chronic sleep deprivation can also make you more likely to develop severe medical conditions.
Research carried out by Harvard University concluded that sleep deprivation is associated with a higher risk of:
- Type 2 Diabetes. This is because sleep interferes with the way in which the body processes glucose. Lack of sleep can cause the body to process glucose far more slowly than it should.
- Heart Disease. Evidence suggests that sleeping less than six hours per night can increase your risk of developing coronary heart disease. This could be because inadequate sleep can raise the blood pressure.
- Mental Illness. As we’ve covered, inadequate sleep can negatively affect your mood. But when this sleep deprivation becomes chronic, a bad mood can transform into a mood disorder. People who don’t get enough sleep are more likely to suffer from depression and anxiety.
- Reduced Life Expectancy. Over a long period of time, inadequate sleep is associated with dying earlier. Sleeping less than 6 hours per night makes you 12% more likely to die prematurely.
Bearing all of this in mind, it’s well worth getting your 8 hours per night. Getting enough sleep is crucial for preventing chronic illness.
What If I Can’t Sleep?
By now, you’ve learned how important sleep is for a healthy lifestyle. The benefits of getting a good night’s sleep are clear, for both the brain and the body. Getting enough sleep will help you to be as physically and mentally healthy as possible. Ideally, you should get to bed no later than 12:30, and sleep for 7 to 9 hours per night.
But what if you’re finding it difficult to get enough sleep? Insomnia – difficulty falling or staying asleep – is very common. To make it easier to fall asleep, try the following tips:
- Establish a sleep schedule by going to bed and waking up at the same time each day.
- Avoid consuming caffeine for at least six hours before bed.
- Avoid screens – such as TVs, computers and cell phones – in the hour before bed. A bright light from backlit screens can trick your brain into thinking it’s daytime.
- Make sure your bedroom is dark, quiet and comfortable. Use earplugs to block out snoring and blackout eye masks if necessary.
- Exercise regularly during the day, but not within 4 hours of going to sleep.
If you’ve tried all of the above, and still have insomnia, you should visit your doctor. They may be able to recommend medication or therapy which could help.