Why We Sleep and How It Is Important For Our Health

Do you think you’re doing all that it takes to ensure a healthy lifestyle? A balanced diet, regular exercise - but are you missing the third pillar of good health, sleep?

You are probably wondering why do we need sleep for a healthy life. We know that it sounds counterintuitive at first because health is all about keeping the body active. Sleeping seems like a passive activity that probably makes you gain weight. And that’s why most people tend to underestimate the role sleep plays in our overall health.

But sleep, or rather good quality of sleep, is actually critical to staying healthy. So, let’s take a look at how and why we sleep.

What is Sleep?

Sleep is a daily recurring period of rest for the body, typically characterised by:

  • a state of reduced consciousness where we have minimal reaction to external stimuli
  • reduced activity throughout the body

Our body temperature goes down, the heart rate is reduced and other bodily functions like metabolism, digestion and respiration also slow down. Brain activity is reduced, with a more regular and synchronous pattern of neuron activation.

Stages of Sleep

Before we understand the stages of sleep, two key terms to know here are Non-rapid eye movement (NREM) and rapid eye movement (REM) sleep.

Sleep also occurs in four distinct stages, moving from light sleep to deep sleep and finally a dream sleep stage, characterised by NREM and REM.

Why We Sleep and How It Is Important For Our Health

Stage 1: This is the steady transition from wakefulness to sleep, and is a very light sleep stage with NREM.

Stage 2: This is a state of well-defined NREM sleep, where the body functions start to slow down, and response to external stimuli and chances of waking up are low.

Stage 3: This is a deep NREM sleep state where the body restores wear and tear in muscles and tissues, and being awakened is a very low possibility.

Stage 4: This is the REM sleep state where you dream, there are rapid brain functions and associated eye movement takes place. This stage energizes the body and mind, and handles memory and learning. It’s easy to wake up during REM sleep, but it leaves the body feeling groggy.

Why Do We Need to Sleep?

Now that we know what sleep is, we can begin to understand why do we sleep. Sleep impacts both our physical and mental health, manifesting in our growth, development, productivity and emotional states. It also performs several restorative functions to ensure that the body is able to perform at its peak.

Here’s a look at how sleep helps the body, and consequently why do we need to sleep:

  1. Conserve energy: As body functions slow down during sleep, it takes less energy to keep the body running and thus helps conserve energy. Being at rest for a set period of time replenishes energy reserves and helps in being more productive when we wake up.
  2. Restore and heal: Studies show that the body performs a lot of repairs while we are asleep. Muscle growth and tissue repairs happen during this period. The body also releases more growth hormone while we are asleep, leading to the body’s development.
  3. Form memories: During sleep, the memories created throughout the day and stored in the short-term memory are moved to the long-term memory. This consolidates the memories we form and creates neural pathways for new learning that’s accessible to us throughout our lives.
  4. Regulate emotions: Sleep also helps rest and rejuvenate the brain and has a major impact on our emotional responses. Our feeling of activeness or lethargy, happiness or anxiety are to a great extent based on our quality of sleep.

Because sleep regulates several critical functions in the body, lack of sleep can have a detrimental effect on us, and this is why we sleep. Here’s a brief look at some of the common disorders that can occur with low quality sleep:

Obesity: Sleep affects the level of hunger and satiety hormones in your body. Lack of sleep increases hunger hormones, pushing the body to eat more than it needs. And that can lead to high BMI and obesity.

Diabetes: Sleep also regulates how your body reacts to insulin and thus has an impact on your blood sugar. Poor quality sleep makes your body resistant to insulin, which leads to high blood sugar, increasing your chances of developing diabetes. Additionally, if you are already struggling with diabetes, lack of sleep can make it difficult to effectively control it.

Hypertension: Studies show that sleeping less than six hours a day increases the chances of developing hypertension. Sleep regulates the stress hormones in the body and hence continued sleep deprivation can cause stress without you being aware of it. This can lead to increased blood pressure and hypertension. It also increases the risk of cardiovascular diseases and stroke.

How much sleep do we need?

While sleep is critical, how much sleep we need changes as we progress through life.Why We Sleep and How It Is Important For Our Health

Because sleep releases the growth hormone and drives the development of the body, babies need a lot of sleep. This goes down as they grow older, but as a whole human beings need the most sleep in their formative years. Young adults (between 18-25 years of age) and adults (between 26-64 years) need about 7-9 hours of sleep on an average. So the oft-repeated advice to get eight hours of sleep a day is actually worth following for a healthy lifestyle.

As you can see, sleep isn’t just a passive activity and actually maintains your body in optimal condition. Also, lack of sleep doesn’t just impact physical and mental capabilities but also causes a lot of imbalances and disorders in the body.

So if you, or a loved one, are feeling the symptoms of fatigue, stress, or daytime sleepiness, or suffering from diabetes or hypertension, it’s wise to check your sleep patterns. You can:

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