How does sleeping affect your cognition?

How does sleeping affect your cognition?


Our brain needs an average of 8 hours of sleep every night to function well. Sleep is more than just a little rest for our brain. It is an essential time for our nervous system to cleanse toxins, improve memory, and repair injuries. 

Nowadays, most people don't get enough healthy sleep and view it as a luxury. But getting less than 6 hours of sleep consistently is not healthy for our brain and body. People who are sleep deprived have increased forgetfulness, mood swings, and even depression.

Understanding what happens with the brain is important to answer the question--why does the brain need sleep?

What's happening with the brain during sleep?


Though we need 8 hours of sleep, our sleep is divided into cycles which include REM or rapid eye movement sleep and non-REM sleep. Each cycle lasts an average of 90 minutes but can go up to 120 minutes. A single night's sleep can consist of four to six sleep cycles. 

During REM sleep, brain activity is high, and this is when we see dreams. But NREM sleep is what is known as deep sleep, as the brain activity decreases considerably. 

When we start falling asleep, our brain enters the first stage of NREM sleep and proceeds to the second, third, and fourth stages. This is when we are in a deep sleep. At the end of around 90 minutes, our brain slowly moves to REM sleep. This is the end of one sleep cycle. Throughout the night, our brain goes through several sleep cycles to prepare our body and mind for the next day.

There are several benefits of sleep ranging from cellular restoration and increased immunity to improved cognition and emotional wellbeing. REM sleep is especially important for learning and memory retention, as this is when our brain processes information.

The relationship between sleeping and cognition


Does sleep affect cognitive function? Yes! It does. While there are several studies that link sleep and cognition, it is common knowledge that good sleep is important for our brain to function effectively. The duration of sleep is important for our cognitive wellbeing. The less we sleep, the more the decline in our cognition. 

Sleep deprivation affects all kinds of cognitive behaviour, right from thoughts and attention, to creativity and imagination. It also decreases our ability to multitask, which affects our day-to-day activities such as driving. 

Similarly, getting consistent, good-quality sleep helps improve our brain performance. Getting uninterrupted sleep every day is shown to improve attention, focus, and memory retention. Apart from this, good slumber is essential for our physical well being. If you want to know what are the benefits of sleep, then read on!

Cognitive benefits of sleeping


For many years, scientists were unsure about one question--how does sleep help your brain? But recent studies have shown that sleep and cognitive function of the brain are interlinked. 

Getting enough good-quality sleep every night is necessary for bodily functions like energy conservation, cell restoration, and immunity-boosting. The effects of sleep deprivation can be immediately recognized in our thinking and perception. 

While sleep deprivation affects some functions more than others, it is shown to decrease all kinds of cognitive abilities. 

Focus and performance

One of the most important cognitive benefits of improving your sleep is increased focus and performance. When we sleep, our neurons reorganize themselves and clear out the nervous system. Just like any other body part, our brain accumulates toxins throughout the day. Clearing it out is imperative for better brain performance. For tasks that require logic and reasoning, good quality sleep is shown to improve performance.

When we sleep enough, our brain is more attentive, resulting in better focus and perception. We think more clearly and are less likely to be confused. Good sleep also helps us make better decisions as we can properly judge our actions. 


Every day, we tend to forget or misinterpret things when we are sleepy. But in the long term, sleep affects our memory retention. REM sleep is associated with memory and learning. When we enter REM sleep, our brain converts short-term memory into long-term memory. This is also when we see dreams, though the exact cause of dreaming is not known.

Not just memory retention, sleeping also helps us forget certain things. Whether we had an unpleasant experience or simply collected unwanted information, our brain gradually erases them as we sleep. This is crucial for our emotional wellbeing, as bad memories can affect our emotional wellbeing. 

Mood and mental health

Sleep activates the brain area that regulates emotions. This is crucial for our emotional stability and overall mental health. Studies have shown that a lack of sleep causes some brain areas, such as the amygdala, to overreact. This part is associated with fear, and an overreaction can cause stress and emotions to take over. 

But the quality of sleep is also affected by our mental health. People who suffer from depression and anxiety also complain of the inability to sleep. In a way, balancing both sleep and mental wellbeing is important for our overall health.

How does the lack of sleep affect your brain?


Proper brain function is not only dependent on sleep duration but also on sleep quality. Our brains require uninterrupted sleep for optimal performance. If your sleep is disturbed or is fragmented, it can negatively affect the brain no matter how long you sleep.

There are practically no benefits of sleep deprivation. If the brain cannot go through sufficient sleep cycles or gets interrupted in the middle of a cycle, we wake up feeling drowsy and tired. This is also a sign that the neurons did not get sufficient time to reorganize and cleanse the nervous system.

Poor quality sleep has both short-term and long-term impacts. While short-term effects can be corrected by getting enough sleep and improving lifestyle, longer sleep deprivation can hamper day-to-day activities and even cause memory loss.

Short-term impacts 

A simple example of how sleep affects cognition is the feeling of drowsiness when we pull an all-nighter. But short-term sleep deprivation can have more impacts than we think. In fact, it is not the skipped sleep but the resulting sleepiness which hampers our cognitive abilities. 

It slows down our ability to think and react, which can affect our everyday activities. While sleeplessness impacts our overall health, certain cognitive functions are affected more than others. 

Lack of sleep also decreases our ability to retain memory. If you have been skipping sleep to study for an exam, it can do more harm than good. Similarly, a complete cycle of 90 minutes is shown to increase memory retention. That is why many people go for power naps to increase their productivity.

Sleeplessness also impacts our creativity. If you are unable to grasp ideas or connect thoughts, this can be an indication that you are not getting enough sleep. It also reduces focus and increases irritability. This can affect your thinking abilities leading to more eros and misjudgments. 

Anxiety and depression can worsen due to improper sleep. People suffering from migraines also report frequent headaches when their sleep is compromised. 

Long-term impacts

While a night or two of bad sleep can be corrected, the long-term impacts of poor sleeping are more harmful. There are no advantages to sleep deprivation. On the contrary, it increases the risk of brain-related diseases such as Alzheimer's. 

There are several irreversible effects of long-term sleep deprivation. Getting less than 6 hours of sleep every night is linked to hypertension, as the body is unable to regulate stress-inducing hormones. This can eventually lead to heart-related diseases, heart attacks, and strokes. Sleep deprivation also impacts our body's ability to produce insulin, which can lead to diabetes. 

The same stress-related hormone, cortisol, can increase anxiety and frustration. People often cope with such problems through binge eating, which leads to rapid weight gain and obesity. Sleep can also cause a change in metabolism, which also contributes to obesity. High cortisol levels can also suppress our immune system, making us more prone to illnesses. 

Sleep deprivation can also cause memory loss, as the brain is unable to convert short-term memory into long-term memory. This can affect our everyday activities and can increase the risk of dementia. 

And in extreme cases, long-term sleep deprivation can cause psychiatric disorders. People who sleep only a few hours a day over a long period of time have reported paranoia and hallucinations, which can be related to schizophrenia.

How many hours of sleep does a person need?


We discussed the sleep benefits for the brain. Getting adequate sleep every night improves our brain functions and helps our nervous system. But how much sleep do we require? The amount of sleep varies from person to person. 

Babies sleep for the longest time, at an average of 15 hours a day. As they progress with age, their sleep requirement also decreases. Young children require about 11 hours of sleep every night. And adults need anywhere between 7 to 9 hours of sound sleep for good health. 

But the amount of sleep doesn't only depend on age but also on a few other factors. The first thing you need to consider is the amount of physical activity involved in your day. Is your work physically demanding, or do you play sports? Then you will require more sleep. People who lead a sedentary lifestyle need less sleep every night. 

Another factor to consider is how healthy you are. If you suffer from depression or other mental health problems or have a higher risk of health issues, then your sleep requirements may vary. 

Despite the widely-accepted recommendations, what is more important is how your body and mind feel after a 7 to 9-hour sleep. If you feel drowsy or irritable or have difficulty staying alert, then you should consider getting an extra hour of sleep. Ultimately, the amount of sleep depends on your requirements.



The effects of good sleep are enormous. It not only helps you feel refreshed but also works to keep your brain and body healthy. Even though the benefits of sleep are widely known, people tend to overlook them and continue leading an unhealthy lifestyle. Many people are unaware of the ill effects of getting inadequate sleep.

Sleep deprivation can not only cause drowsiness and frustration but also contribute to health problems. Diabetes, hypertension, anxiety, and depression are all linked to a lack of good quality sleep. 

Sleep can feel like a luxury, especially when you don't have time. But it is important to acknowledge that your body and brain need rest to function effectively. Consistent, quality sleep can not only improve your cognitive abilities but also enhance your emotional and physical wellbeing.


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