Brief science of sleep

Source: https://time.com/collection/guide-to-sleep/

Sleep is a naturally recurring state of mind and body, characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and inhibition of nearly all voluntary muscles during rapid eye movement (REM) sleep, and reduced interactions with surroundings. It is distinguished from wakefulness by a decreased ability to react to stimuli, but more reactive than a coma or disorders of consciousness, with sleep displaying very different and active brain patterns. Sleep occurs in repeating periods, in which the body alternates between two distinct modes: REM sleep and non-REM sleep. A well-known feature of sleep is the dream, an experience typically recounted in narrative form, which resembles waking life while in progress, but which usually can later be distinguished as fantasy.

Statistics from the National Sleep Foundation have illustrated the amount of sleep required for different age groups. Healthy adults are advised to sleep between 7 and 9 hours per night. Babies, young children and teens need even more sleep to enable their growth and development. People over 65 should also get 7 to 8 hours per night.

Source: https://www.sleepfoundation.org/articles/how-much-sleep-do-we-really-need

For being essential for survival, sleep is a highly conserved behavior across animal evolution. For example, while normal rats live for two to three years, those short of REM sleep have their lifespan of only about 5 weeks on average, and it is even worse for rats lacking all sleep stages that live only about 3 weeks. Sleep-deprived rats also develop abnormally low body temperatures and sores on their tail and paws due to the rats’ impaired immune system. Besides, sleep allows our nervous systems to work properly, as too little sleep leaves us drowsy and unable to concentrate the next day. It also reduces the efficiency at work and makes people distracted from doing brainy jobs such as doing math calculations. Therefore, sleep is bound to give the brain time to refresh and rest to fully-function during the next day without any disturbance.

Moreover, deep sleep coincides with the release of growth hormone in children and young adults. Many of the body's cells also show increased production and lessened breakdown of proteins during deep sleep. Since proteins are the building blocks needed for cell growth and for repair of damage from factors like stress and ultraviolet rays, deep sleep may truly be "beauty sleep." Activities in parts of the brain that undertake emotion controls, decision-making processes and social interactions are drastically reduced during deep sleep, suggesting that this type may help people maintain optimal emotional and social functioning while they are awake. As a result, people who stay up late or have little sleep are usually short-tempered and unwilling to communicate.

Lack of sleep may lead to a lot of other risky diseases such as stroke, asthma and Alzheimer’s disease or even mental disorders such as depression, epilepsy and schizophrenia. Some of them often appear at old age but nowadays, young people suffering from these are increasing in number. The explanation lies in their lifestyle: little sleep, improper eating, little exercise and many more. Thus, it is highly recommended that people should not delay and discard their sleep time as well as other activities in order to lead a healthy life.

Reference: https://www.medicinenet.com/script/main/art.asp?articlekey=79735

Author: Nguyen Thanh Nam, High School for Gifted Students