Is the brain more active at night?

In this brief guide we are going to answer the question ‘’Is the brain more active at night?’’ we will discover what tasks the brain performs while the rest of our body rests and we will mention the consequences of not getting enough sleep.

Is the brain more active at night?

Yes, there are major changes in brain electrical activity while we sleep.

One afternoon in 1885, like so many others, the chemist Friedrich August Kekulé fell asleep by the fireplace. He had been trying for a long time to decipher the architecture of some molecules and, although he had managed to find some, others, such as benzene, were resisting him.

During that little nap, he began to dream of atoms and molecules, which joined together and formed chains that twisted, twisted, intertwined. One of these chains took the shape of a snake that bit its tail in a circle and spun on itself at high speed. Upon awakening, Kekulé saw that he had just found the solution to the problem of the chemical structure of benzene.

Something similar happened to Dmitri Mendeleev, who was inspired by a dream of the periodic table of elements; or the doctor Otto Loewi, whom the pillow made him find a neuroscience experiment, thanks to which he ended up winning the Nobel Prize in Medicine.

The list of telltale dreams doesn’t stop there. Perhaps Frankenstein would not exist if Mary Shelly had not dreamed of him, nor would we know The Strange Case of Dr. Jekyll and Mr. Hyde, by Robert Louis Stevenson.

Even Beethoven and Paul McCartney had many of their melodies hitting them while they slept. And Gandhi explained that the inspiration to begin his peaceful protest to achieve the independence of India came precisely from dreamlike places.

Although dreams are often bizarre and incoherent, other times they can lead us to solve problems. Conventional wisdom already says, which recommends consulting any kind of mess with the wise pillow. 

And it’s that in most cases, eight hours of restful sleep can make us wake up with a clear mind, capable of elucidating an answer or finding a creative solution to a puzzle.

For centuries it was believed that when sleeping, simply, the brain unplugged and entered a dead time in which nothing happened. But that explanation didn’t seem to make evolutionary sense.

Why should we have to devote more than a third of our lives to lethargy with the things to which we could dedicate those wasted hours? In addition, that semi-conscious state left us totally vulnerable to possible attacks.

All animals also sleep. Some close to 20 hours a day, others just three or four. There are even them, like dolphins, who sleep first with one half and then with the other half of the brain. Nature, then, must have its motives.

Why do we sleep?

Experiments and studies conducted in the last decades have shed light on this topic. Now science knows that sleep is crucial, as is eating. 

Without sleep, we would die in a few days and sleeping little or badly compromises our state of health, our emotions and even relationships. Good rest is a kind of intensive cure for the physical, mental and emotional organism.

It improves our mood, mood, the immune system, recharges us with energy, and even makes us look better. It also clears the mind, allows us to enjoy new experiences, acquire information and come up with creative solutions. It is also the tool that evolution has endowed us with to learn.

Dreaming to learn At the end of the 19th century, the German psychologist Hermann Ebbinghaus saw for the first time that secret nocturnal life of neurons.

After several experiments and observations, he pointed out the possibility that perhaps sleeping served to consolidate what we had learned in the day, prevent us from forgetting it, and prepare ourselves to learn the next day.

But the scientific community dismissed the idea as nonsensical. The brain, they claimed, simply shut down.

A century later, in the 1950s, two researchers at the University of Chicago, Eugene Aserinsky and Nathaniel Klietman, tested that theory. Several experiments allowed them to show that during rest, the brain continues to work at full speed.

They saw that in certain phases of sleep, such as REM (rapid eye movement), large-scale waves were generated similar to those produced when we are awake. They also observed that groups made up of thousands of neurons were activated in a synchronized way from one to four times per second during the so-called slow sleep phase.

So it seemed that the brain was anything but inactive. But what was it doing?

What does the brain do while we sleep?

Although we are not aware of it, the brain continuously scans the environment in search of useful information; it collects data non-stop and accumulates it so that it can later be used. And while we sleep, that information capture stops and the brain is dedicated to processing everything that it has acquired during the day.

It combs the recently formed memories, analyzes and scrutinizes them, discards those that he considers irrelevant, and enhances, reinforces and classifies those that may be useful to us the next day.

However, how this task is carried out remains a mystery to neuroscience. We know that memories are formed by establishing connections between several hundred, thousands or even millions of neurons, creating patterns of activity.

Those patterns, when reactivated, lead to that memory, from where we left the car keys to when World War II ended. Moreover, during the hours of sleep, not only are memories fixed, but also only those details considered most relevant are dissected and saved.

Sleep and memory

For that to happen and we can efficiently retrieve the memory, it must have been well fixed and the first hours after its acquisition are crucial. Apparently, the brain stores the information that it captures in the hippocampus, which works as a kind of temporary memory. And there he keeps it until he decides whether to delete or save it.

While it is in the hippocampus, it must compete with many other memories for a gap, with a series of synapses between neurons. If the process fails and the memory is not fixed well, it will have interferences; that is, it will be mixed with other memories.

And that will be a disaster, because every time we try to evoke it, we will reactivate similar neural patterns and the memory we get will be adulterated with others.

Sleep is essential to consolidate new learning and it has been proven that it is better remembered after a good rest.

Recent studies with rats have shown that in those animals that had learned to solve a maze, the activity of their brains while they slept, during the REM phase of deep sleep, was very similar to what they had when they were learning to solve the maze. That suggests that learning circuits could be strengthened during sleep hours.

In fact, many musicians find that if they practice a particularly difficult score before going to sleep, when they get up in the morning they are able to interpret it better. In a 2005 study, the brain activity of pianists who were playing sheet music was monitored using imaging technologies.

Regions such as the left cerebellum, the motor cortex, the hippocampus and the prefrontal cortex were seen to be activated, all of them areas responsible for the speed and precision of the fingers on the keyboard. And it was also those areas that were most active when the musicians slept.

The brain kept going back over the synapses that had been established during learning to reinforce them. Hence, the next day, it was easier for the pianists to play that score. And the same goes for students before an exam.

Those who study and then rest for eight hours tend to obtain better results than those who stay up all night.

Eight hours daily

Thomas Edison considered sleeping a complete waste of time. And both Napoleon and Margaret Thatcher boasted that they hardly needed to close their eyes for about four hours each night.

Without a doubt, getting a good night’s sleep is important to maintaining a healthy life. But how many hours of sleep is the optimal measure? It depends on the age. For example, babies sleep about 17 hours a day, while children and adolescents need, on average, nine hours.

Most adults require about eight hours, although this number normally decreases with age, as does the depth and continuity of sleep.

Sleep deprivation, depending on its duration and intensity, causes serious havoc. After more than 15 continuous hours of wakefulness, we begin to experience cognitive decline, which results in problems concentrating and a slow reaction rate, similar to a drunken state.

In the long term, little or bad sleep deeply affects our biology and can ruin our health. In fact, it cuts down on our longevity. Affects the immune and nervous systems. And diabetes, obesity and cardiovascular problems are some of the consequences related to insufficient rest. While we sleep, the brain is responsible for getting rid of the metabolic waste produced during the day.

Without enough rest, we do not give time to clean and the body accumulates garbage. The lack of hours of sleep triggers the secretion of cortisol, the stress hormone, which, in excess, is related to abdominal fat. 

It can also end up disrupting metabolic functions, such as carbohydrate processing and storage; the body stops metabolizing sugar well, which increases our risk of developing type 2 diabetes. Endocrine Eve van Cauter, from the University of Chicago School of Medicine, investigates the effect of sleep on the body. 

In an experiment with young volunteers, she found that if she restricted their sleep to four hours a night, a week later the participants were already in a prediabetic state. Also, they had much more appetite. 

But that sleeping is good and necessary does not imply that the sheets have to stick to us. Sleeping more than necessary on a regular basis is also not beneficial for the body. 

In fact, quite the opposite: more than nine hours of sleep per day for an adult carries as many health risks as sleeping less than seven and is closely related to high morbidity.

So, is the brain more active at night?

A sleeping brain doesn’t rest. A study conducted by Harvard University found that the levels of adenosine triphosphate (fundamental chemicals for supplying cells with energy) in the brain remain fairly constant while a person is awake, but they increase for a moment the moment the individual falls asleep.

Instead of resting, the brain returns to full capacity. Sleeping provides an initial energy boost.

This increased energy is used during the night to create and reorganize the connections between neurons.

Therefore, while some areas of the body remain less active while the person is sleeping, the brain uses more energy.

FAQS: Is the brain more active at night?

Is the brain more active during sleep?

As we could see, when we sleep, the brain remains highly active. While we sleep, sleep allows the removal of toxins that are built up while you are awake.

At what time is the brain most active?

The brain is most active between 10:00 am and 2:00 pm, at this time, our cognitive abilities are at their maximum thanks to the high level of cortisol.

Why is my brain so active at night?

You probably suffer insomnia. Thinking excessively while we sleep is very common, especially when we are under stressful situations. Our brain is alert, watching for something important to happen.

How does brain work during sleep?

Many processes take place during sleep: Neurons reorganize, the brain throws away old information. The body repairs itself and recovers energy.

Where does our mind go when we sleep?

While we sleep, the brain is active by carrying out activities such as deciding which memories to keep, etc. Our brain continues to work, and sometimes reconstructs memories that produce dreams.

In this brief guide we answered the question ‘’Is the brain more active at night?’’ we discovered what tasks the brain performs while the rest of our body rests and we mentioned the consequences of not getting enough sleep.

If you have any questions or comments please let us know!


Brains Learn Better At Night. (2020). Retrieved October 16, 2020, from ScienceDaily website:,time%2C%20when%20recovery%20is%20maximised.

Brain Basics: Understanding Sleep | National Institute of Neurological Disorders and Stroke. (2019). Retrieved October 16, 2020, from website: