There has been some debate about whether or not sleep is the single most important factor in life, but there is growing evidence that the brain depends on sleep in other ways.
In particular, we have found that the brain uses sleep as a backup to the brain, because we evolved from mammals who were active during the day and who got very little sleep. Because the brain depends so much on sleep, it might do so even without a big amount of sleep, since sleep is an important backup in the absence of much sleep.
Some people are convinced that all brains work like clockwork. For some reason our brains evolved in such a way that it takes little sleep to operate. This means that our brain uses sleep to protect itself from getting worn down. We also know that sleep is important for memory and for the processing of other factors we have no obvious way to measure.
There is some evidence that sleep may even be critical for the development of the brain in its initial stage. It would seem that sleep should play a major role early in life to prevent the brain from growing too big and to enable the brain to learn the skills needed for survival. But in fact, the brain is growing at too fast an rate and there is only a small period in between birth and when the brain starts to grow, during which the brain is actually not growing any more than it already has.
This problem is solved by short sleepers, as their brains only grow by a degree, while longer-term sleepers still do not sleep enough to prevent the brain growing too big.
If we can learn that the brain is constantly getting a lot of sleep, we can then come up with solutions that will help it to get the sleep it needs to work. This would mean that we can have a big impact on the problem of sleepiness, as more sleep would mean a more active brain and a bigger brain that would be better able to do other things.
There is also a very simple solution to the “why does the brain use sleep as a backup to the brain” problem. This is that the brain never becomes totally inactive. As I said earlier, our brains are constantly changing and their activity is influenced by several different factors, some of which are more important than others. But our brain does have one factor which can be reliably used to predict how much our brain will change: sleep.
The brain can be seen as a large collection of circuits. Each circuit contains several neurons and their output. Each neuron has a connection to a certain set of neurons and its output is an electrical signal which can then be interpreted in different ways.
If the input of a circuit is fixed and no new input can enter that circuit until it is completely shut off, then there is always a certain level of activity to be expected. But with the brain, the input is constantly changing. This means that a certain number of cells of a certain set of neurons always have a certain degree of activity. We have a name for this “set of neurons which do not change”: the “no change” set. The brain can use this set of neurons to predict what other set of cells of a certain cell type will do in the future.
This idea has been used for decades to predict changes and to develop new therapies for the control of disease. If we can show that the brain always enters a certain state while sleeping, then we should be able to predict exactly what happens in sleep. It would help us to better understand what part of the brain is essential to sleep. With enough sleep, we would understand more about the brain.
If we can’t predict what will happen in sleep, then we have a solution – we just need to sleep longer.
More information on the brain is available at our Brain Archive. This contains a lot of information on sleep and brain development, including:
How our brain wakes up
A brief history of sleep research
The concept of sleep
Protein kinase A phosphorylation in the hypothalamus
Sleep and memory
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