It is a point on which everyone agrees, from sleep experts to everyone else who sleeps. Above all, sleeping allows rest and removes fatigue. A bit basic of an answer? And yet, everyone knows that being rested rather than exhausted ensures that they are more responsive, better able to learn and interact throughout the day. A question remains: Why do we feel rested and how does sleep regenerate our body at night?
Several hypotheses have been made to explain this restorative function of sleep.
The oldest is based on the replenishing of energy stocks. Every cell needs the energy to function. This is particularly true of neurons which alone account for 20% of the total energy consumption of our bodies. This energy is not free in the body. It is carried by the chemical bond of a small molecule called ATP (adenosine triphosphate). When needed, it fuels the energy-consuming cellular reactions, transforms into adenosine diphosphate (ADP). It is then regenerated to ATP through the degradation of different large energy-rich molecules: creatine in muscles, glycogen in the brain and so on.
But this regeneration is relatively slow. During awakening, the activity of our neuronal cells is intense. They consume ATP faster than it can be regenerated. Gradually, as the day moves along, the available energy resources decrease. In parallel, the ADP accumulates in the brain and it is this accumulation that increases the need for sleep and pushes us to go to bed. It is the signal that it is time to clean the circuits and refuel!
Sleep as the “cleansing” phase of the brain and the body
A more recent hypothesis is that of sleep as the “cleansing” phase of the brain. Like any cell, the neuron carries out biochemical reactions. It degrades large molecules into smaller molecules of interest, creating “cellular waste”. During the day, high neuronal activity will tend to cause these co-products to accumulate in the neuron and in the fluid in which it bathes. Since neurons are very sensitive to the quality of their environment, some of these wastes may have toxic effects.
A system of channels will drain them out of the central nervous system, but this process is very slow. In 2013, an American research team showed that this cleansing process accelerated during sleep due to a 60% increase in spaces between neurons. The restorative aspect of sleep could, therefore, be the consequence of this greater elimination of the neurotoxic products, ensuring the preservation of the integrity and the good functioning of the brain cells.
Dreem’s action in improving the quality and quantity of your deep sleep will play on these two tables to ensure a more restful sleep and thus a more effective awakening.