We spend about one third of our lives sleeping. You may think sleeping is just a “natural habit” that everyone has but in reality, it’s a complex, highly regulated process that’s essential for our survival and healthy daily functioning.

There has to be a good reason why we’ve evolved to spend a considerable amount of our time sleeping. In fact, there are many. And in this article, we’ll look at 5 benefits of quality deep sleep according to science.

But before we dive into that, it’s important to discuss obstructive sleep apnea, which is the most common breathing disorder that disrupts sleep. Obstructive sleep apnea occurs due to an overgrowth of tissue around the throat, which impairs breathing.

Obstructive sleep apnea is more common than you think —  it has a prevalence of as high as 30% (for males) in the US. And it can deprive you of all the benefits of sleep we’re about to discuss.

If you have been suffering from excessive daytime sleepiness, you may very well have obstructive sleep apnea. The first-line treatment for the condition is a CPAP device, which prevents your airways from collapsing as you sleep. Make sure to consult a doctor for your symptoms.  

But for now, let’s discuss what deep sleep is and how it benefits you.

What is deep sleep?

You may think every time you fall asleep, you get to enjoy adequate deep sleep. This is a misconception and arises from a lack of knowledge about something called sleep architecture.

Sleep is a highly regulated and complex process. When you sleep through the night, your brain and body activity goes through several changes, which divides sleep into several stages. These stages make up the sleep architecture.

The first stage of sleep is called N1, which occurs right after you fall asleep. During N1, the activity of your heart, brain, and eyes slow down. After about 7 minutes in N1 sleep, you slip into deeper sleep called N2 sleep.

During N2 sleep, metabolic activity in different body areas continues to slow down. And this is the sleep stage where you spend most of your time while sleeping each night. 

Then comes N3 sleep — this is the true “deep sleep” that we’re talking about. During N3 sleep, the metabolic activity inside the body is at its lowest. The brain, heart, and lungs all relax maximally during N3, which makes N3 the most important sleep stage in terms of sleep quality.

If you fail to transition into N3 sleep, you will not feel fresh when you wake up. That’s because this is the sleep stage where the body performs cell and tissue repair which prepares you for the moment you wake up the next day. Interestingly, this is also the stage where people sleepwalk!

After N3 sleep, you transition into a sleep stage called REM sleep, which is characterized by increased brain activity and rapid side-to-side movements of the eye. This is the stage where most of your dreams occur.

After REM sleep, you go back into N1 sleep and the cycle restarts. Each night, you go through multiple cycles made up of these sleep stages.

What are the benefits of quality deep sleep?

We’ve already discussed one benefit of good deep sleep — the repair of tissues and cells, which allows us to feel rested when we wake up. Without good deep sleep each night, you’ll wake up tired and won’t be able to function optimally during the day.

This can have a wide range of consequences depending on what you do and how much responsibility you have.

But repair of tissues and cells is not the only thing that happens when you sleep. Let’s take a look at some more benefits of deep sleep.

1. Sleep can minimise the risk of diabetes

Sleep can help prevent diabetes by keeping your bodily functions and energy in check. While you sleep, the brain releases a hormone called leptin, which makes you feel full. When you’re sleep deprived, the body increases the production of a hormone called ghrelin, which acts on the brain to make you feel hungry.

Sleep deprivation makes people eat more, gain unhealthy weight, and be at an increased risk for diabetes. So, if you’re looking to lose some weight it may be a good idea to get some extra shut eye and wake up fresh for the day!

2. Sleep strengthens your immunity 

You may have heard a lot about all the supplements and vitamins you can take to improve your immunity during the COVID-19 pandemic.

In reality, one of the best things you can do to improve your immunity is get enough sleep. When you sleep, your body upregulates the production of molecules called cytokines.

Cytokines allow white blood cells to communicate with each other — in other words, they regulate the immune system, allowing you to mount better defenses against invading pathogens.

Antibodies and white blood cells are also produced in greater amounts during sleep, both of which help you fight off infections. 

3. Sleep decreases stress 

Stress and anxiety can both partly result from the brain’s overreaction to normal stimuli. The part of the brain associated with emotions is called the limbic system and consists of structures like the amygdala, cingulate gyrus, and hippocampus.

During sleep, the activity of the limbic system increases, which is thought to promote emotional stability and well-being. In people who are sleep deprived, this emotional regulation fails, which gives rise to stress and anxiety.

4. Sleep allows your brain to reorganize information

We accumulate a lot of information (and memories) over the day. Some of this information is useful, while most of it is not. For efficient functioning, it’s important that the brain gets rid of all the useless information you acquire over the day and consolidate only the important memories. 

When you sleep, the nerve cells and the connections between them — the synapses — get reorganized. The brain also gets rid of toxic chemicals accumulated during the day and deletes useless information.

Finally, sleep also helps the brain convert short-term memories into long-term, which is essential for learning. This makes good deep sleep particularly important for students. 

In the end, you should know that chronic sleep deprivation is associated with a variety of health problems, including hypertension, weight gain, increased risk of injury, and increased levels of the stress hormone cortisol.

All of these can have negative consequences on your health in the long run and now that you’re aware of the benefits of sleep, make sure you get plenty of it each night!