In the previous article we said that “sleep is a mysterious process”, citing the words of biologist David Prober. And indeed, though we sleep every night and sleeping seems like a very simple act, nothing is further from reality. Sleep is a process full of unknowns and questions for which science still has no answers. Perhaps the most important question is why do we need sleep?
Contrary to what you may think, sleep is not a passive state of the body. While we are sleeping the body’s activity does not stop until the next day. During sleep, the brain activity continues and new bodily functions, biochemical and metabolic changes necessary for the functioning of our body occur.
Sleep unfolds in cycles. A complete sleep cycle takes approximately 90 to 100 minutes and it can be repeated 4 or 5 times during the night. Each sleep cycle has five stages (transition to sleep, light sleep, deep sleep transition, deep sleep and REM where dreaming occurs).
Each sleep stage has a specific biological function. However, the answer to the question of why we sleep at night remains an enigma.
Why do we need sleep?
Here are some interesting theories that you may not know about.
Sleep, a primitive method to avoid danger
This is the oldest theory and suggests that the fact that we sleep at night is a survival mechanism. Night is when we are most vulnerable to predators because we are not adapted to night time. While we are sleeping we move away from danger.
According to this theory, sleeping at night facilitates survival.
This theory suggests that sleep is necessary to remedy the deterioration of the body that happened during the day. Functions that have deteriorated during the day recover throughout the night.
Tissues are restored, proteins are synthesized and cognitive and neurological functions are restored.
Studies of complete sleep deprivation in animals show that animals lose their immune system and die within a few weeks.
At night it is more difficult for humans to get food. While we are sleeping a decrease in body temperature and calorie needs occurs and we use less energy.
However, his theory is not sufficient in itself. The energy saving of a person at night is only 10% (120 kcal) compared to the day.
This theory is more recent and argues that sleep is directly related to brain plasticity, that is, the brains’s ability to change its organization and its structure by age. Therefore, according to this theory, babies sleep a lot (between 13 and 14 hours per day).
Regardless of these theories, all researchers agree that sleep plays a vital role probably related to neuronal integrity and remodeling synaptic connections.