When we sleep, what is happening in our body 

Actively Asleep

For many decades, scientists believed that people were both mentally and physically inactive during their sleep. Fortunately for us, scientists now know that this is not correct. Throughout the whole night, both our body and brain are responsible for carrying out many critical functions in our health that are key to our well-being.

There are two main types of sleep we have during our sleep. It is during the night that we cycle in and out of these as we sleep. Hence as the name suggests as we sleep through cycles. The two primary cycles are REM (otherwise known as rapid eye movement) and non-REM sleep.

Non-REM Sleep

At the beginning of the night, we begin in non-REM sleep. It is also where we spend most of your rest time too. It starts light, in the “N1” stage, and then proceeds to move to the deep “N3” stage.

What we have discovered is that during this progression, the brain becomes less responsive to its surroundings. Meaning it is much harder to wake up at that point. At the same time, all your thoughts and most of our body functions have slowed down. About half our typical night’s sleep occurs in the “N2” phase. Scientists also believe it is during this point of sleep that we file & store our long-term memories.

REM Stage

REM stage, or otherwise rapid eye movement, not surprisingly got its name due to the way our eye movements increase, darting backward and forward behind our eyelids. It is I this stage that we dream the most. Our pulse, blood pressure, body temperature, and breathing rise again to similar daytime levels. The sympathetic nervous system, whose role is in helping with our automatic responses, such as the “fight or flight,” becomes highly active. However, our body during this stage will stay almost entirely still.

Sleep Cycles

During our sleep, we typically rotate through all these sleep stages—between three to five times in one night. The first REM stage initially may just a few minutes; however, it becomes longer with each new occurring cycle. The cycles are lasting up to about half an hour as we near the end of our sleeping.

N3 stage, however, on the other hand, do the opposite, with these tending to become shorter with each new occurring cycle. Scientists have also discovered that should we lose out on REM sleep during our sleep, for whatever the reason, our body tries to recoup what it has missed out on by trying to make it up the next following night. The exact purpose of this is currently unknown by Scientists. Research is continuing, and hope to find an answer soon.

Body Temperature

It is as we become drowsy before bed, our body temperature drops by a couple of degrees. It is also at it is lowest at roughly around 2 hours before wakening. One function of REM sleep is our brain turning off our body thermometer. It is due to this occurring that we affected more to heat or cold in your bedroom. In the conclusion of this discovery, it is proven to be better to have a cooler room when you sleep as it helps better sleep to occur.


Our breathing throughout the day, of course, can change a lot. As we fall into a deeper sleep, our breathing becomes much slower and more regular. When we enter the REM stage of our sleep, our breathing gets faster and more varied.

Heart Rate

It is during a night of deep, non-REM sleep that your blood pressure and the pulse lowers. Therefore, giving both the heart and blood vessels a vital chance to rest and recover. However, it is during the REM cycle that those rates can go back up or change around.

Brain Activity

By closing our eyes, we begin to drift off into non-REM sleep. Our brain cells start to settle down after the daytime activity levels by firing the neurons in a much steadier, rhythmic pattern. However, after this occurs, we begin to dream. Meaning the brain cells start firing actively and randomly again. While we are in REM sleep, a reading of our brain activity is the same as when you are awake.


In addition to all the above, for thousands of years, we have spoken about dreaming. However, even today, they are still very much a mystery to us in many ways. Therefore, scientists are not sure what causes them to occur or even if there is a purpose.

It is occurring during REM, mainly if it is a very visual dream. However, it is also possible for a dream to happen during other sleep stages as well—for instance, night terrors. Night terrors are when a person appears to be awake; however, crying out in fear or panic—occurring when in much more profound states of sleep.

Time to Repair

In addition to the above, during sleep, the body works to repair itself, the muscles, organs, and other cells. It is strengthening the immune system by circulating chemicals around via our blood. A fifth of your night’s sleep is spent in deep sleep while you are young and healthy, which increases if you have not slept well or enough. However, this ability starts to fade, so when you are over 65, this could be down to zero.

Take Out the Trash

Scientist believes that this is what REM sleep does. During this cycle, our brain has a clear out of the information we no longer need. The belief comes from research that asked people to do a challenging puzzle. They discovered that those doing so found it easier to complete it after they slept rather than before. In addition to them being able to recall more facts and complete tasks much better, too. Noted was also that those taking part that had been deprived of REM sleep, in particular, lose a more significant advantage when compared with a loss in other sleep stages being.


Brainstem plays a crucial role in many aspects of our sleep. It is by talking to the hypothalamus, which is another part of the brain’s structure, that allows and helps us to drift off and wake up. Through this communication with each other that the chemical called GABA is created. GABA production that quietens the “arousal centres” so should this not happen it can be responsible for keeping you from sleeping. During REM sleep, the brainstem’s role is to send signals to the muscles that move our arms, legs, and body—causing the temporary paralyzation of those muscles. This prevents you from physically acting out of the dream.

Hormone Symphony

The body also makes more of certain hormones during our sleep while lowers others. For instance, the growth hormone levels will go up, while cortisol, the one tied to stress, will go down. Many scientists now believe that insomnia is related to a problem in the body’s hormone-making system.

Similarly, it is proven that a lack of sleep can alter levels of other hormones. Specifically, the hormones that control hunger. These being leptin and ghrelin. When those changes occur, this will significantly affect how much you eat, and then weight gain occurs.  

Where to now?

In other words, sleep is not merely the act of lying flat on your bed. There are multiple aspects and functions to sleep. When one part of that is not working as it should, it throws the rest off as well.

The good news is that it does not have to be this way. You can find out if you have a hormone imbalance that could be causing your sleep issues, weight gain, detrition in your health and well-being, and many more issues by clicking here.  

Taking this quiz now will help you find out more and then how I can help you get your sleep back on track and your health back where it should be.

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