Decreases stress

Many people live with significant anxiety and stress. In scientific terms, this means high levels of the stress hormone cortisol released by the body. Likewise, when an individual lacks sleep, their cortisol levels increase. And this is where the stress-sleep cycle can come into play; a lack of sleep is more likely to stress people, hampering their ability to sleep well the next night. 

But by getting good sleep, people reap the benefits of lower cortisol levels, naturally helping them feel more relaxed.

Improves attention

Nothing replaces sleep to maintain proper alertness. It is illusory to want to be wide awake without getting enough sleep in sufficient quantity and quality. Sleeping conditions attention, the ability to adapt and react as well as availability. Fragmenting sleep lengthens reaction time, promotes errors and impaired judgment. The resulting drowsiness has short-term, often serious consequences.

Many industrial disasters can be explained by sleep debt. The explosion of the space shuttle Challenger in 1986 is an example of an accident due to human error and improper decisions related to lack of sleep.

Restores energy

For some scientists, the main purpose of sleep is the repair of physiological processes damaged during waking time. Thus, the duration of sleep lengthens when the body is heavily used (intense physical effort, pregnancy, puberty).

For others, sleep makes it easier for the brain and its nerve connections to rest, which is made less efficient by a prolonged period of wakefulness. Sleeping protects against the accumulation of stress and allows the reconstitution of an energy capital. 

Finally, deep sleep contributes to the elimination of toxins and other wastes from the brain, respiratory, cardiovascular, and glandular systems. It has been shown that during deep sleep the brain areas are the site of a real neuronal washing which eliminates amyloid substances and proteins, both involved in neurodegenerative diseases such as Alzheimer’s.

Strengthens the immune system

Various studies have shown that people who sleep well are less susceptible to diseases and recover faster when they get ill. This is because the amount of sleep has a direct impact on the immune system. Especially the deeper sleep phases play an important role in this.

The production of proteins and hormones

During slow sleep, the production of certain proteins is increased (notably insulin and growth hormone). Thus, it is during sleep that a child actually grows. Also, the first hours of the night are very important, the slightest disturbance can hinder the production of these hormones. A decrease in slow deep sleep caused by untreated sleep apnea syndrome can lead, subsequently, to a break in the growth curve in children.

Adaptation to the environment

Behavioral studies, both in humans and animals, attribute a role to sleep in adapting to the environment: sleep deprivation weakens our immune system and contributes to an increased susceptibility to infections. The circadian clock maintains a stable equilibrium in the face of exterior changes. 

It is based on the immutable principle that there can be no continuous activity without periodic rest, and it coordinates the rhythmic activities of our body. For example, our sleep follows a day/night rhythm, our skin renews its cells during the night (with a peak around 1 am), and the secretion of gastric enzymes anticipates meals.

Maturation of the nervous system

The duration of REM sleep is very important in newborn children. This sleep would be used for the establishment and development of nervous circuits, therefore for cerebral maturation which is very rapid during fetal life and the very first months of life. The proportion of paradoxical sleep in fact drops from 50% of sleep time at the 36th week of fetal life, to 20% in adults.

Maintains a healthy skin

Sleep helps erase the signs of aging. Of course, a good night’s sleep doesn’t erase wrinkles with the snap of your fingers. However, several bad nights of sleep can alter the quality of the skin and weaken it. Thus, wrinkles will appear more often. Sleeping well, therefore, helps to maintain supple, healthy skin and a fresh complexion.

Limits weight gain

People who don’t get enough sleep are more likely to gain weight. Indeed, lack of sleep or poor quality of sleep affects the general condition and the feeling of satiety. This changes the production of hormones that control appetite. The stomach secretes ghrelin, a hormone that stimulates the feeling of hunger, in large quantities.

The risk of snacking and the desire to consume fatty food are then more present than after a good night’s sleep. When the lack of sleep is regular, bad habits set in, promoting weight gain. Recent studies also show that a lack of sleep promotes the storage of fat and reduces the ability to eliminate it.

Increases libido

Sleeping well can really boost your libido for several reasons. To begin with, good quality sleep helps keep testosterone (the hormone mainly responsible for sexual desire and erectile capacity in men) high. Several studies have shown that a man who sleeps less than 6 hours a night has less testosterone than a man who gets enough sleep. As a result, he then feels a decrease in sexual desire.

The second reason is due to the communication and analysis of the desires of his partner. When we are tired, we simply tend to favor sleep over sex and ignore the needs and desires of our partners. Lack of sleep can also cause you to be irritable: in this case, couples’ relationships sometimes deteriorate, drastically reducing the likelihood of having sex.

Builds yours personality

REM sleep has a lot to do with the behaviors we have that are important to us humans, but also at our personal level (acquisition of professional learning in particular). It can also be a means of adaptation and prevention to dangers.

Improves memory

This field is the subject of much controversy, not on the obvious contributions of sleep to memory and learning, but on the nature of these contributions. Slow sleep reinforces existing memory while REM sleep rather increases the capacity for new memories. Experiments have shown that memory capacity is better when there is a period of sleep after the learning phase.

Increases performance

Whether physical or intellectual, the quality of one’s performance is linked to that of sleep. Athletes must sleep well the nights before competitions or else they will perform poorly. In addition, studies report that a lack of sleep increases the symptoms of fatigue (decrease in glycogen stocks, muscle damage, pain, etc.). It has also been shown that insufficient sleep can also increase the likelihood of injury.

Prevents Driving accidents

Maintaining attention is essential when it comes to road safety. A 1997 Australian study compared the driving behavior of sleep-deprived youth with others who had consumed alcohol. The conclusion is clear: after 24 hours of prolonged wakefulness, cognitive performance decreases to the same level as a blood alcohol level of 1g/L.

A more attractive appearance

It probably won’t surprise you. Getting enough sleep will make you look more attractive. It prevents pale skin, swollen eyes, and dark circles that often accompany a lack of sleep. In addition, a good night’s sleep ensures that you produce less cortisol. This so-called stress hormone ensures that skin collagen is broken down, making the skin less elastic and smooth.

The effect of too little sleep on appearance has been demonstrated in a Swedish study, among other things. This study showed that subjects who slept too little for only two nights are already rated as less attractive and unhealthier.

Increases life expectancy

A good night’s sleep ensures a longer life. This has been established by various studies. For example, researchers at the University of Pittsburgh have found that the time it takes you to fall asleep, the number of times you’re awake at night, and the amount of “deep sleep” affect your life expectancy.

In another study, more than 10,000 Britons have been followed for 20 years. This research showed that people who sleep only 5 to 7 hours per night are twice as likely to die early. This was partly due to a greatly increased risk of a heart attack. Other studies have found that the likelihood of other deadly conditions such as stroke, diabetes, and dementia also increases due to a lack of sleep.

Prevents inflammation

The next answer to the question ‘why is sleep important?’ has to do with inflammation. Sleep can have a major impact on inflammation in the body. Sleep deprivation is characterized by the increase of undesirable characteristics such as inflammation and cell damage. Too little sleep is strongly linked to long-term inflammation of the digestive tract (sourcesource).

One study found that patients with Crohn’s disease who were denied sleep were twice as likely to relapse than those who did sleep enough (source). Researchers even state that a sleep evaluation can help predict outcomes in people who have long suffered from inflammation-related illness (source).

Nate Douglas

Nate has worked as a nutritionist for over 14 years. He holds a Master's Degree in dietetics from the University of Texas. His passions include working out, traveling and podcasting.