Why do we have to sleep
Research suggests that sleep helps learning and memory in two distinct ways:
- A sleep-deprived person cannot focus attention optimally and therefore cannot learn efficiently.
- Sleep itself has a role in the consolidation of memory, which is essential for learning new information.
Although the exact mechanisms are not known, learning and memory are often described in terms of three functions:
- Acquisition refers to the introduction of new information into the brain.
- Consolidation represents the processes by which a memory becomes stable.
- Recall refers to the ability to access the information (whether consciously or unconsciously) after it has been stored.
Each of these steps is necessary for proper memory function. Acquisition and recall occur only during wakefulness, but research suggests that memory consolidation takes place during sleep through the strengthening of the neural connections that form our memories.
When we sleep we are almost disconnected from the external world, we do not process the information of our senses. It seems that this time is used by the brain to consolidate new memories. It may look that the brain is finding an equilibrium to maintain old memories while adding the new ones (to avoid catastrophical forgetting).
I find interesting that the younger the person the more sleep it needs. This is specially obvious in babies where they have to sleep many times a day.