Sleep is a vital function of the body, along with breathing, digestion or immunity

Sleeping: a vital function
Sleep is a vital function of the body, along with breathing, digestion or immunity. It also plays a key role in the state of well-being in the day.
Sleep is not a continuous state: it consists of 4 to 6 sleep cycles, each of which takes about 90 minutes in adult (in a healthy subject). each sleep cycle including several phases: slow sleep (light or deep), then paradoxical sleep.
At the end of each cycle, there may be a short awakening, followed by a new sleep cycle or, sometimes, a complete awakening.
Deep slow sleep is more recovering; it is more abundant in the first 3 or 4 hours after sleep than in the second half of the night.
Slow sleep: body recharge batteries
During slow sleep, the body and brain are at rest. Brain activity and muscle tone decreases then, while the body recharges itself with sugar in anticipation of a new day. It is also during this phase that growth hormone, also called somatotropin, a child’s growth hormone, but also useful throughout life, especially for tissue repair.
Paradoxical sleep: ′′ The night gives advice ′′
During the paradoxical sleep phase, the body is at rest but the brain is awakening. This is the dream area: if you observe someone during their paradoxical sleep, you can see their eyes moving. This phase plays an important role in long-term learning and memory, and allows children to ′′ put their files in order ". This is why children are often advised to read a lesson before they can bed, to better hold her back the next morning.
So sleep plays many roles for our body, besides the obvious rest of the body and mind.
The roles of sleep
Maintaining vigilance on the watch
Toxin removal
Maintenance of body temperature
stimulation of immune defences
Reconstructing muscle and nerve cell energy stocks
Mood and stress activation regulation
Hormone production including growth and melatonin
Learning and memorization mechanisms
Regulating functions such as blood sugar (and appetite)
The importance of sleep in child development
From birth, the life of the baby is beaten by the alternation of the two basic physiological states: watch and sleep. As in adults, sleep is organized in cycles with restless (paradoxical) and calm (slow) sleep succession. But, unlike adults, the night starts with paradoxical sleep, and ends with slow sleep. It is as the child develops that sleep will reorganize to acquire the same structure as the adult.
The crucial role of sleep on the physical and cognitive development of children is well known today. In the first few months of life, sleep will allow the baby’s brain to finish ripening, and in parallel to grow. These basic steps explain the important amount of sleep needed in babies (about 14 hours per day). Indeed, at birth and in the first period of life, the baby sleeps almost all day, alternating sleep stages and awakening stages. It is during this time that its biological clock located in the brain will be set, thanks to the indicators of time (alternating light darkness, regular time of bottles, interaction with parents…)
It’s starting at 6 months that sleep starts to organize like adult: paradoxical sleep comes later in the cycle and becomes more important at the end of the night, and slow sleep locates more and more more in early sleep cycles. This slow sleep is important because growth hormone is synthesized during this phase.
From 1 to 3, sleep maturation continues. Deep slow sleep increases (36 % of sleep time) especially early night, and paradoxical sleep decreases to reach age 3 that of adult.
Different needs by age
The National Sleep Foundation (NSF), a U.S. sleep research organization, is proposing a benchmark to determine how much sleep is needed for everyone, according to their age. This range is a simple benchmark, since it doesn’t take into consideration the specificities of each individual.
US NSF specialists, with a panel of multidisciplinary experts, in anatomy, physiology, pediatrics, neurology, gerontology and gynecology, have reached consensus, after examining scientific data, on this recommended sleep duration according to age groups … The objective of these clinical guidelines is obviously to improve the quality and quantity of sleep to reduce the occurrence of diseases related to deprivation, disorder or irregularity of sleep and / or disturbance of the biological clock.
Newborns ages 0 to 3 months: 14 and 17 hours a day
Infants ages 4 months: 12 and 15 hours per day
Small children ages 1: 11 and 14 hours per day
Pre-school children ages 3: 10 hours per day
School age children ages 6: 9 hours per day
Teens ages 14: 8 hours per day
Young adults ages 18: 7 hours per day
Middle aged adults ages 26: 7 hours per day
Seniors ages 65 and up: 7 to 8 hours per day
What to remember: Sleep is vital for the body and provides a large number of physiological functions.
Slow sleep (most restorative) in adults is rather early night (around 3nd and 4rd hours after sleep).
Child’s sleep presents important changes from birth to preschool age (3-5 years), especially to ensure physical and cognitive developmen