This is What Happens to Your Body When You Sleep 8 Hours a Night

While it's true that some people can function on less than eight hours sleep, research has found that most people benefit from around eight hours each night. In addition, each of the four chronotypes—aka the four most common natural sleep patterns that scientists have observed in humans—can differ in what a "full night" of sleep means. For example, Bear chronotypes reliably require a full eight night after night, whereas Dolphin chronotypes can be highly productive on less than eight hours of sleep.

Generally speaking, eight hours is the sweet spot. Too much sleep can lead to headaches, body pain, poor concentration, low mood and fatigue. Likewise, not enough sleep can weaken your immune system, increase weight gain and affect concentration.

For most people, banking approximately eight hours of shut-eye every night can be a good way to support overall health and wellbeing.

Here is what can happen to your body when you sleep eight hours a night.

You'll strengthen your immune system

With the coronavirus pandemic of 2020 enhancing our awareness of immune health, much has been said about the importance of sleep in regards to preventing illness and infection. University of Queensland researchers writing for The Conversation earlier this year confirmed that most adults need between seven and nine hours of sleep at night.

"Sleep and our circadian system (or internal body clock) are essential for regulating our mood, hunger, recovery from illness or injury, and our cognitive and physical functioning," they say. "Declines in the quality and/or quantity of sleep can affect our immunity, leaving us more susceptible to illnesses including viruses."

They explain that while we sleep, the immune system releases proteins called cytokines, which are important for fighting infections and inflammation, and help us respond to stress. When we don't get enough sleep, or our quality of sleep is sub-par, our body produces fewer cytokines, leaving us more at risk of getting sick. 

You're less likely to gain weight

You know the feeling. You've been sleeping terribly at night and spend the day overdoing it in the treats department, or helping yourself to an extra bowl (or two) of pasta at night. Lack of sleep can lead to hormonal imbalances, which can make it harder to practice healthy eating habits. One study from the Current Opinion in Clinical Nutrition & Metabolic Care scientific journal found that sleep loss has been shown to result in metabolic and endocrine alterations and increased hunger and appetite.

The link between poor sleep an obesity is real. "Sleep is an important modulator of neuroendocrine function and glucose metabolism," the study states. The restorative value of sleep, not just for the body but for the brain, is vital to support good eating habits and the body's ability to process food effectively.

You'll experience better moods

It's enough for just one bad night to ruin your mood, but if you're regularly getting less than a solid eight hours, or your eight hours is unpleasant and full of interruptions, then you can look forward to near continual irritability, poor concentration and lack of energy. You may find yourself overreacting, getting into arguments, and feeling low-key anxious about anything and everything. In some cases, this can even raise the risk of developing some mood disorders, says an a Better Health government report. Constant bad moods caused by sleeplessness often reinforce the already poor quality of sleep, or make it worse, which can make it a difficult cycle to break out of.

When you get a full night's sleep, on the other hand, you can find that your mood improves. Not only will you find that your baseline irritability level goes from a 9 to a 1, but the fact that your comprehension and concentration skills are better off can allow you to feel more capable and be more productive, which can then improve your mood even more so. If sub-par sleep is affecting your mood, know that once you break the negative cycle you may very well fall into a positive cycle full of stable, steady and sometimes even happy moods daily.

You'll lower your risk of heart disease and diabetes

According to a government report, the effects of long term sleep deficiency can also increase the risk of chronic health problems such as heart disease and diabetes. Another study from the Current Cardiology Reviews journal found that people in Western countries are sleeping on average of 6.8 hours per night, which is 1.5 hours less than a century ago.

"Recent epidemiological studies have revealed relationships between sleep deprivation and hypertension (HT), coronary heart disease (CHD), and diabetes mellitus (DM)," the study says. "Adequate sleep duration may be important for preventing cardiovascular diseases in modern society."

You'll increase your productivity

"I definitely believe there is a sleep crisis in our culture," says biology professor and neuroscience expert Dr Matthew Carter. "Most people equate losing sleep with having more time to enjoy the day or getting things done. Ironically, when they are sleep deprived, they enjoy the day less and are so unfocused that they are much slower in getting things done."

Poor productivity due to poor sleep is another vicious cycle that can be difficult to break out of. The less productive you are when you're awake, the longer it takes you to complete the tasks required of you, and the less time you have to relax and sleep. According to a 2014 study by the US National Sleep Foundation, poor sleep is causing 23 to 45 per cent of the population to lose more than two work weeks worth of productivity every year.

Get a solid eight hours of quality sleep and you will likely find that tasks both simple and complex are easier to complete and it's easier to stay organised and use your time efficiently.  

Are You a Dolphin or a Lion? How Knowing Your Chronotype Can Boost Your Productivity.