The reason people have to sleep

People need sleep because it is a necessary condition to maintain normal levels of cognitive functions such as speech, memory, creative thinking and flexibility.

"Why do we sleep" is a question that confuses scientists for centuries, and the answer is 'no one really knows for sure'. Some scientists believe that sleep helps the human body recover from an active day, but in fact the amount of energy saved after eight hours of daily sleep is very small - about 50 kcal, equivalent to an amount energy in a piece of toast.

What will happen if people do not sleep

The best way to understand the role of sleep is to look at what happens if we don't sleep. Lack of sleep seriously affects the ability of the brain to function. If you stay up all night for a long time, your personality will become gruff, or whining, uncomfortable and forgetful. After only one sleepless night, your concentration level will become more difficult, the time to concentrate also significantly shortens.

In real-life situations, serious consequences from the lack of sleep by employees are believed to contribute to some international disasters such as Exxon Valdez, Chernobyl, Three Mile Island and Challenge, exploding the shuttle.

Artwork: mindbodygreen.com

Insomnia not only has an impact on cognitive function, but also on mental and physical health. It can cause disorders such as difficulty breathing, stress and high blood pressure, and insomnia increases the risk of obesity because of hormones and enzymes that control appetite and weight gain created during sleep.

What happens when we sleep

Sleep occurs in 90 to 110 minute cycles and is divided into two stages: non-REM sleep (the first stage of sleep) and REM sleep (the later stage of sleep).

Non-REM sleep is divided into 4 small stages. At the first stage (drowsiness) is the first stage of sleep, it lasts about 5-10 minutes, the person will be in a semi-conscious state, muscle activity will slow down and twitch slightly may happen, we are easily awakened at this stage.

Second stage (light sleep), human eyes stop moving, breathing and heart rate start to slow down.

Stage three and four are called deep sleep . In it, in the third stage, the brain works with a wave of delta wave with a large amplitude and low frequency, the lowest breathing rate and heart rate. Stage four is characterized by rhythmic breathing and limited muscle activity. If we are awakened at this time, we will not be able to adjust our body immediately but often feel groggy and disoriented for a few minutes after waking up. Symptoms such as nightmares, sleepwalking, some children often enuresis occur at this stage.

After going to sleep for about 70 to 90 minutes, people fall into REM sleep. Typically, each person has between 3 and 5 REM periods per night. This is the time when most dreams occur, at which point the eyes move, breathing and blood pressure increase.

So how much sleep is needed?

There are no specific numbers about daily sleep time that applies to everyone. The results of sleep study records indicate that people usually sleep between 5 and 11 hours a day and an average of 7.75 hours. Jim Horne, from Loughborough University's Sleep Research Center, said: "The amount of time an individual needs to sleep is a time for him to not feel sleepy during the day when he works."

Even animals need to meet the demand for an average sleep time a day, the tiger species is 15.8 hours respectively; cat species 12.1 hours; chimpanzee 9.7 hours; 3.8-hour sheep, African elephant, 3.3 hours, deer 1.9 hours.

The current world record for 11 days without sleep belongs to Randy Gardner in 1965. After the first 4 days he began to hallucinate, followed by illusion that he thought he was a famous football player . Surprisingly, Randy experienced quite well and worked normally on the final days of the competition.