The fetus also has a sleeping and waking moment in the mother's womb, but most of the time is in sleep. According to sleep EEG observation, REM sleep takes up most of the time.
Newborn sleep 14 to 16 hours every 24 hours, about half time of them in REM sleep, we can see their eyes move back and forth clearly when they sleep. It was also the rapid eye movements of newborn babies that scientists discovered REM sleep. When newborn sleep, in addition to the rapid eye movement, you can see that they often clench their fists fingers or toes, make faces or smiles while they're dreaming, it's a pity that we cannot understand the newborn's dream.
In conclusion, the analysis of the sleep electroencephalogram (eeg) from the fetus to the newborn shows that REM sleep is important for the growth and development of the central nervous system.
As the child grows, till preschool, the child's sleep time is reduced to about 12 hours in preschool and one hour nap. During puberty, sleep is reduced further to 9 to 10 hours and no longer nap.REM sleep decreases with increasing age, and the proportion of sleep is reduced throughout the night.
Generally speaking, if the child is bright and cheerful during the day,no tired appearance, it's probably said that night sleep is enough.
The average adult sleeping time is eight hours, and men need seven to nine hours, while women are slightly longer, nine to ten hours. A slight different of men and women, men need 7 to 9 hours, women slightly longer, 9 to 10 hours. Actually the differences in sleep time between men and women depend on objective conditions.
For example, during a woman's pregnancy, pregnant women sleep more than normal because of the increased hormone progesterone in pregnancy. Women's sleep is lighter than men's and is easily wakened, so it is easy to suffer from insomnia. In the menopausal period, the phenomenon of insomnia is more prominent, becoming a major characteristic of climacteric syndrome.
There are corresponding changes in the sleep structure of adults at night, the total time of REM sleep continues to decrease, the period that appears also decreases, generally accounting for about 1/6 of total night sleep time. The cycle is also reduced, only about a sixth of the total nighttime sleep.
People always think that older people need less sleep, this is not entirely true.Indeed, the old NREM the Ⅲ and the Ⅳ period decreased significantly, Sometimes even without the first Ⅲ NREM and first Ⅳ period, Only the first Ⅰ and first Ⅱ period, And wake early in the morning, The total sleep time is only five to six hours per night.
But it's not proved that older people need less sleep time, only for 24 hours of sleep EEG examination found that older people often have shallow sleep during the day, maybe they use this way to catch up the sleep deprivation at night.
We often found that old man who was reading the newspaper to listen to music watch TV lowered his head and closed his eyes gradually , sometimes even snoring softly, drooling, this is the old shallow sleep, they were to catch up the sleep lost during the night.
All in all, a person's life from birth to time of death, sleep is absolutely necessary, but the time, structure and content of the sleep has a rather complex change with age.