By Riccardo Montesanti
Did you know that sleep determines most of our day? Rest presents several exciting and complicated scientific studies in our everyday life. Sleep is an essential component of a person's life: it is the time we recharge both the brain and the physical body and allow them to get ready to face what waits for them the next day. The alternation between sleep and wakefulness is regulated by various mechanisms, including a homeostatic process that tracks the need for sleep in proportion to the previous waking state's duration. During sleep, metabolic activity slows down while the brain's toxic proteins are excreted during the waking phase. These wastes are drained through the intercellular spaces that increase during sleep to allow for drainage. They will then be sent to the liver, which will dispose of them.
How much sleep do we need?
It is well known that sleeping many hours promotes the body's capability for various activities, but is it fair to think that sleeping more is better? Not really, every age has a recommended number of hours. According to scientific research, the number of hours to devote to sleep decreases with the years' passing. Teenagers, for example, should sleep between 8 to 10 hours; for those over 65, it is recommended to sleep 7-8 hours, infants, those ranging from 0 to 3 months should sleep 14-17 hours a day.
Two types of sleep? What are they? How do they work?
There are two types of sleep, REM sleep (rapid eye movement) and non-REM sleep. Non-REM sleep has four phases that occur cyclically, each of which has a specific kind of brain wave and neuronal activity. The first phase is the transition from wakefulness to sleep; in this phase, the heartbeat and breathing slow down, brain waves become slower, and the muscles relax. Phase two, also known as light sleep, precedes deeper sleep; in this phase, the body temperature is reduced, and brain waves are slower but interrupted by intense peaks of activity. The most profound sleep period occurs in the third and fourth stages, which is the most important: the heart rate and respiration reach the minimum rate and the muscles are relaxed to the maximum. At this stage, the brain waves slow down further. The REM phase, on the other hand, begins about 90 minutes after falling asleep: heart rate, brain activity, and blood pressure are similar to the waking state and the muscles are temporarily paralyzed. This is the stage where most dreams occur.
What role does the brain play in sleep?
Some parts of the brain manage the sleep process; among these, the most important is the hypothalamus, which contains groups of neurons that control sleep and wakefulness. The hypothalamus is the most important communication centre between the nervous system and the endocrine system. Another vital part of the brain is the brain stem, which communicates with the hypothalamus to control the transition from wakefulness to sleep. It also plays a crucial role in REM sleep by sending signals to the muscles, causing them to relax. The thalamus also plays a vital role during non-REM sleep, it is quiescent, isolating the body from the outside world; during non-REM sleep, it is activated by sending many sensations cortex that come to life in dreams. The pineal gland, which is remarkably close to the hypothalamus, receives some signals and increases melatonin production, a hormone that helps you fall asleep when it gets dark. Finally, there is the basal forebrain which provokes sleep and wakefulness. The release of adenosine from some cells stimulates falling asleep. Caffeine contrast sleep by blocking the action of adenosine. Unfortunately, it is not always possible to sleep without problems. There are numerous disorders, including insomnia, hypersomnia, respiratory diseases, heart rhythm disorders and movement disorders.
What happens if we don't get enough sleep?
If we don't sleep, the consequences on our daily life are severe. The lack of sleep leads us to feel tired and to be more irascible. The effects of inadequate rest include memory loss, headaches, stress, decreased attention, alertness, and even hallucinations. So when we don't sleep, we are much more fragile.
In conclusion, sleep is a fundamental component of our life that, by resting the body, allows us to face even the most challenging days.
Some studies have found that:
- In America, China, Russia and most of Europe, the average sleep varies between 7 and 7.30 hours.
- In South America between 6.30 and 7 hours.
- In Australia, they sleep on average from 7.30 to 8 hours a night.
