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Why Is Sleep Important?

Now more than ever, people are sleeping less than they did in the past; and quality of sleep has also decreased over the years. Getting the right amount of quality sleep is as important as other biological functions essential to life, such as eating healthy and exercising. When we sleep, our body performs many vital processes that aid in physical and mental recovery and repair.

People often go through periods in life where they struggle to get good quality sleep. Lifestyle commitments, stressful events, worries and physical conditions are all factors that can affect our natural sleep process. Did you know that up to 4 in 10 Australian adults aren’t getting enough good-quality sleep?

How Much Sleep Do We Need?

The amount of sleep we need generally varies from person to person. The number of hours also adapts to each individual’s needs and circumstances. For an adult, the average amount of sleep per night is 7-9 hours. However, individual needs can range between 5-10 hours per night. Not sure how much sleep you need? Take a look at the recommended sleep times for each age category below:

AgeRecommended Hours of Sleep 
Newborn (0-3 months old)14 – 17 
Infant (4-11 months old)12 – 15 
Toddler (1-2 years old)11 – 14
Preschool (3-5 years old10 – 13
School-age (6-13 years old)9 – 11 
Teen (14-17 years old)8 – 10
Young Adult & Adult (18-64)7 – 9
Older Adult (65+) 7 – 8 

Source: https://www.sleepfoundation.org/how-sleep-works/how-much-sleep-do-we-really-need

We judge the quality of our sleep based on how we feel and function throughout the day. If we don’t feel fatigued, then we can assume our sleep was adequate, despite it maybe not being for the average length of time. Generally, the most effective and restorative effects of sleep come from within the first three to five hours, which is when we experience the most ‘deep sleep’. 

Even with good quality sleep, no one can function at peak performance every moment of the day. It’s completely natural to experience fluctuations in performance and mood during the day. Our body’s circadian rhythm, which we often refer to as our ‘body clock’, controls when we feel tired or awake. Even with adequate sleep, many people begin to feel sluggish or drowsy after lunch. This is a natural response to our body’s circadian rhythm which makes us feel tired around 2 am and 2 pm. When this rhythm becomes disrupted, as an example from shift work or jet lag, you can experience sleep problems. Have you ever wondered what happens to your body and mind when you sleep? Let’s find out.

What Happens When We Fall Asleep?

During the night we experience two different types of sleep:

Non-REM – non-rapid eye movement

REM – rapid eye movement

Non-REM sleep occurs first, followed by REM sleep, then the cycle repeats. Within each of these types of sleep, we make our way through a 4 stage cycle. Each stage of the sleep cycle is linked to specific brain waves and neuronal activity. Every night, you’ll typically cycle several times through the non-REM and REM sleep type stages. Let’s go through these in more detail. 

Stage 1 Non-REM Sleep: In this stage, you transition from wakefulness to sleep. This period usually lasts 5 – 10 minutes. Your heart rate, breathing and eye movements will slow, and your muscles start to relax with occasional twitches. Brain activity will slow down from their daytime processes and patterns. During this period you can easily be woken.

Stage 2 Non-REM Sleep: In this stage, you’re in a light sleep before entering a deeper sleep. Your body slows down and relaxes even further. Your body temperature will drop and eye movements stop. Brain activity slows but has brief bursts of electrical activity. During the repeated sleep cycle process, you spend the most amount of time in this stage. This moderate sleep stage lasts for about 30 – 45 minutes. 

Stage 3 Non-REM Sleep: This is the final stage of non-REM sleep, and is when you’re in your deepest sleep throughout the sleep cycle. This type of deep sleep satisfies our sleep needs the most effectively. During this stage, your body performs numerous health-promoting tasks such as tissue repair and growth, cell regeneration and the strengthening of your immune system. 

Stage 4 REM Sleep: REM sleep first occurs approximately 90 minutes after falling asleep. During this stage your eyes move rapidly from side to side behind closed eyelids, hence its given name, rapid eye movement sleep. Your heart and breathing rate increases, as well as your blood pressure. In REM sleep, our brains become very active and usually experience vivid dreams during this time. Our arm and leg muscles also become temporarily paralyzed. It is thought that this is a neurological barrier preventing us from ‘acting out’ our dreams. 

Quick Recap: 


Stage 1: light sleep

Stage 2: moderate sleep 

Stage 3: deep sleep or slow-wave sleep 


Rapid eye movement or dreaming sleep

Benefits and the Importance of Good Sleep

The benefits of good quality sleep is an almost endless list. There’s no denying that we all know sleep is important. But how in-depth do we understand its benefits? Let’s explore these in more detail below:

Improves Brain Function

We’ve all experienced a poor night’s sleep. This means you can relate when I say how foggy your mind feels the day after. It’s not surprising to anyone that sleep significantly impacts our brain function. Adequate sleep is vital for what experts like to call ‘brain plasticity,’ which in non-scientific terms, means the brain’s ability to adapt to input. 

For more than 100 years, scientists and researchers have studied the complex relationship between memory and sleep. While you sleep, your brain sorts through memories from the previous day, filtering out what’s important and removing irrelevant information. When you don’t get enough sleep, you start to experience the effects of sleep deprivation, including memory loss. Less, or poor sleep, means the brain doesn’t have enough time to create new pathways for the information we’ve learned or experienced during the day. Therefore affecting how memories are consolidated.

Not only does adequate sleep improve how we process and store memories and information, but it also enhances all aspects of brain function. This includes cognition, concentration, productivity, performance and problem-solving skills.

Physical Health

So, now we understand that sleep is incredibly important for the brain, what does it do for the body? The relationship between sleep and physical health has been well researched and documented. When we sleep, our body performs different processes than it does compared to when we’re awake. Instead, it prioritises and promotes recovery and repair. 

While asleep, our body generates protective, infection-fighting defences like antibodies and cytokines. These substances are vital to combat invasions from bacteria and viruses. Sleep deprivation prevents your immune system from being able to build up these defensive forces. This in turn will affect your body’s ability to fight off the nasties and may also mean your recovery from illness is longer. It’s been proven that even a slight loss in sleep can impair the body’s immune function.

Maximise Athletic Performance

To perform at their absolute best, athletes must prepare in every aspect of their life. Alongside regular training and eating healthy, making time for rest and recovery is equally important. Increased quantity and quality of sleep improves performance in many aspects of the physical demands of sport. Let’s take a look at some recent findings:

  • Male basketball players who extended their regular sleep schedule to 10 hours per night were able to run faster in sprints and also improve their shooting accuracy by 9%. 
  • Both male and female swimmers who extended their sleep to 10 hours had improved reaction times off the diving blocks, and also showed an increase in kick strokes. This contributed to quicker 15-meter sprint times. 
  • University tennis players who increased their sleep to 9 hours experienced improved serve accuracy from 32% to 42%. 

Across all studies, athletes reported feeling less sleepy throughout the day and experienced improvement in their overall physical and mental well-being. Just as good quality sleep has positive effects on performance, poor quality sleep has negative ones. Including:   

  • Hindered ability 
  • Decrease in accuracy
  • Increased rate of fatigue/exhaustion
  • Slower reaction times 
  • Difficulty making decisions and problem solving 
  • Higher risk of injury
  • Lower resistance to fight off illness

Sleep Deprivation

Doctors encourage you to get enough sleep for very good reasons. When you get less sleep than what your body needs, or no sleep at all, it’s called sleep deprivation. A small bout of sleep deprivation, such as one night of lack of sleep, isn’t a major cause for concern. However, frequent or prolonged sleep deprivation can seriously affect your health. 

We know that lack of sleep negatively affects brain function; including your mental abilities and emotional state. You’ll become irritable, impatient, prone to mood swings and experience poor cognitive function. What many people fail to realise is that sleep deprivation may also increase your risk of chronic conditions such as diabetes, high blood pressure, heart disease and stroke.

We’d also like to highlight the dangers of driving when suffering from sleep deprivation. Lack of sleep affects your ability to make decisions and decreases your reaction time, increasing your likelihood of being in an accident. Drowsy driving accounts for thousands of crashes, injuries and fatalities every year.

The Bottom Line

Sleep is essential, there’s no doubt about it. It’s vital to maintaining optimal health and physical and mental well-being. Good quality sleep can also improve athletic performance and decrease your risk of being in a car accident. Unfortunately, there are times in life when our natural sleep process is interrupted. This can be both equally exhausting and frustrating. Stay tuned for part 2, where we will go into detail about how you can improve your quality of sleep through good sleep hygiene habits. But until then, how many hours of sleep do you do?

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