Sleep is an important part of any person’s life. If a person can live without food for several days, and some people even for weeks, then without sleep this figure is much lower. The longest period of wakefulness without a break for sleep was recorded at around 19 days, but this is more of an exception to the general rule. An ordinary person, even after one sleepless night, does not feel very well: concentration of attention decreases, the activity of the nervous system slows down, severe fatigue, apathy, dizziness and headaches bother. If the next 2–3 nights dream for some reason it also does not occur, then various serious depressive disorders may occur, there is a risk of developing hallucinations and nightmares.
Ideal sleep duration
Modern medical science is of the opinion that optimal sleep duration in an adult is 6.5–7.5 hours. If a person sleeps less than 5 hours a day, then this threatens his health, and there is evidence of a reduction in life expectancy in this category of people. First of all, the nervous system and metabolism suffer. However, an excessively long sleep is no less harmful to the body than a short one. In the group of people who spend more than 9.5 hours in bed, life expectancy was also lower than in those who sleep less. It’s no secret that the Japanese are long-lived. Perhaps the reason for this is that one of the most important daily rules for them is regular sleep of about seven hours.
Immediately before sleep there is a state of falling asleep or drowsiness, which is well known to everyone. It is manifested by yawning, a decrease in the level of consciousness, a slowing of the pulse, a decrease in the activity of the endocrine glands. If the environment is conducive, then the person then falls into a dream.
During sleep, certain parts of the brain are activated — somnogenic, while the rest of the parts are resting. During sleep, there are 2 phases:
1. Slow-wave sleep (orthodox, synchronized), which takes 70–80% of the total sleep time in duration. In non-REM sleep, the following phases are distinguished:
Stage I — relaxed wakefulness and drowsiness,
Stage II — superficial sleep,
Stage III — sleep of medium depth,
Stage IV — deep sleep.
Waking up a person in stages I and II is quite easy, while in stages III and IV a person is very sound asleep.
2. REM sleep (desynchronized), taking up 20–30% of the time, respectively.
During REM sleep, a person’s eyeballs move and he sees dreams.
The fast and slow phases replace each other, and for the whole night a person alternates 4–6 cycles. The first two cycles of non-REM sleep are the deepest, and later cycles are less deep, so the longer a person sleeps, the easier it is to wake him up.
Normal dream provides a person with good health, mood and is simply necessary for the normal functioning of all organs and systems. In no case should you neglect 7–8 hours of sleep daily for the sake of work, doing household chores or watching TV at night.