Sleep is essential for good health. However, why does sleep take so much time out of the entire 24hrs day? What is its purpose?
We need sleep to survive — just like we need food and water. Let’s have a look closely at what type of biological processes happen during sleep:
The brain stores new information and gets rid of toxic waste.
Nerve cells communicate and reorganize, which helps a healthy brain function properly.
The body repairs cells, restores energy, and releases hormones and proteins.
These processes are critical for our overall health. Without them, our bodies can’t function correctly. We are talking here about muscle repair, tissue growth, protein synthesis, and the release of many of the important hormones for growth, all occurring primarily during sleep.
What happens if we don’t get enough sleep?
First of all, let’s look closely into one question: Why do we sleep?
To date, scientists have found that sleep helps the body in several ways:
Energy Conservation
Research suggests that 8 hours of sleep for human beings can produce a daily energy savings of 35 % over complete wakefulness.
The energy conservation theory of sleep suggests that the main purpose of sleep is to reduce a person’s energy use during times of the day and night when it’s inconvenient.
Body Restoration
Have you heard about the restorative theory? which says the body needs sleep to restore itself.
The idea is that sleep allows cells to repair and regrow. This is supported by many important processes that happen during sleep, including:
Muscle repair
protein synthesis
tissue growth
hormone release
Brain Function
When you sleep, your brain’s system clears out waste from the central nervous system. It removes toxic by-products from your brain, which build up throughout the day. This allows your brain to work well when you wake up.
Research suggests that sleep contributes to memory function by converting short-term memories into long-term memories, as well as by erasing, or forgetting, unneeded information that might otherwise clutter the nervous system. That is why sleep is equal to body and mind functions.
Sleep affects many aspects of brain function, including:
learning
memory
problem-solving skills
creativity
decision making
focus
concentration
Emotional Well-Being
During sleep, brain activity increases in areas that regulate emotion, thereby supporting healthy brain function and emotional stability.
Research shows that on the one hand, sleep disturbances can contribute to the progression of mental health issues, but on the other hand, mental health issues can also contribute to sleep disturbances. We recommend having a sleep-improving TO DO list telling what to do so you can enjoy a good sleep.
Weight Maintenance
Sleep affects your weight by controlling hunger hormones. These hormones include ghrelin, which increases appetite, and leptin, which increases the feeling of being full after eating.
During sleep, ghrelin decreases because you’re using less energy than when you’re awake.
Lack of sleep, however, elevates ghrelin and suppresses leptin. This imbalance makes you hungrier, which may increase the risk of eating more calories and gaining weight.
Recent research shows that chronic sleep deprivation, even as few as five consecutive nights of short sleep, may be associated with increased risk of:
obesity
metabolic syndrome
type 2 diabetes
Proper Insulin Function
Insulin is a hormone that helps your cells use glucose, or sugar, for energy. But in insulin resistance, your cells don’t respond properly to insulin. This can lead to high blood glucose levels and, eventually, type 2 diabetes.
Sleep may protect against insulin resistance. It keeps your cells healthy so they can easily take up glucose.
The brain also uses less glucose during sleep, which helps the body regulate overall blood glucose.
Heart Health
While the exact causes aren’t clear, scientists think sleep supports heart health. This stems from the link between heart disease and poor sleep.
The Centers for Disease Control and Prevention (CDC) says the average adult needs 7 hours of Trusted Source of sleep a night. Getting less than that on a regular basis can lead to health problems, many of which can hurt your heart health.
What happens when you sleep and what are the stages of sleep?
When you fall asleep, your brain and body go through several cycles of sleep. Each cycle includes four distinct stages.
The first three stages are part of non-rapid eye movement (NREM) sleep.
The last stage is rapid eye movement (REM) sleep.
The NREM stages used to be classified as stages 1, 2, 3, 4, and REM. Now it’s generally classified in this way:
N1 (formerly stage 1): This is the first stage of sleep and the period between being awake and falling asleep.
N2 (formerly stage 2): The onset of sleep begins at this stage as you become unaware of your surroundings. Your body temperature drops slightly, and your breathing and heart rate become regular.
N3 (formerly stages 3 and 4): This is the deepest and most restorative sleep stage during which breathing slows, blood pressure drops, muscles relax, hormones are released, healing occurs, and your body becomes re-energized.
REM: This is the final stage in the sleep cycle. It takes up about 25 percent of your sleep cycle. This is when your brain is most active and dreams occur. During this stage, your eyes move back and forth rapidly under your eyelids. REM sleep helps boost your mental and physical performance when you wake up.
It takes, on average, about 90 minutes to go through each cycle. If you can complete five cycles a night, you’d get 7.5 hours of sleep a night. Six full cycles are about 9 hours of sleep.
Ideally, you want to wake up at the end of a sleep cycle instead of in the middle of it. You usually feel more refreshed and energized if you wake up at the end of a sleep cycle.
Sleep keeps us healthy and functioning well. It lets your body and brain repair, restore, and reenergize.
If you don’t get enough sleep, you might experience side effects like poor memory and focus weakened immunity, and mood changes. That is so important to increase a deep sleep.
Why is Sleep Important?
Sleep is crucial for many reasons. A good night’s sleep:
regulates the release of hormones that control your appetite, metabolism, growth, and healing
boosts brain function, concentration, focus, and productivity
reduces your risk for heart disease and stroke
helps with weight management
maintains your immune system
lowers your risk for chronic health conditions, such as diabetes and high blood pressure
improves athletic performance, reaction time, and speed
may lower your risk of depression
Scientists agree that sleep is essential to health, and while stages 1 to 4 and REM sleep are all important, deep sleep is the most essential of all for feeling rested and staying healthy.
The average healthy adult gets roughly 1 to 2 hours of deep sleep per 8 hours of nightly sleep. There are various ways to gauge whether you are, from personal trackers to a sleep study.
Cappuccio FP, et al. (2011). Sleep duration predicts cardiovascular outcomes: A systematic review and meta-analysis of prospective studies. DOI: 1093/eurheartj/ehr007
Ellenbogen JM. (2005). Cognitive benefits of sleep and their loss due to sleep deprivation. DOI: 1212/01.wnl.0000164850.68115.81
Greer SM, et al. (2013). The impact of sleep deprivation on food desire in the human brain. DOI: 1038/ncomms3259
Hirshkowitz M, et al. (2015). National Sleep Foundation’s sleep time duration recommendations: Methodology and results summary. DOI: 1016/j.sleh.2014.12.010
