What is the meaning of sleep for humans and animals? Is it a "shutdown restart"?

Biotech Engineering Channel: Introduction: Scientists have come up with a lot of ideas about why we should sleep.
is a way to save energy; there are also those who believe that sleep offers the opportunity to remove brain cell waste; and there is a view that sleep simply forces animals to lie down calmly to avoid detection by arrested eaters.
new research suggests that sleep is about the brain's self-editing, deleting useless memories, and providing new space for intellectual functioning and memory storage.
study also found that while sleeping pills help people sleep, they may also interfere with the natural editing of synapses in the human brain during sleep.
is the meaning of sleep? Sleep is about forgetting something you learn during the day: The brain edits itself when people are asleep, trimming neuron synapses that form when they're awake during the day, according to new research.
years, scientists have come up with a lot of questions about why we should sleep.
say sleep is a way for people to save energy.
say that sleep brings an opportunity to remove brain cell waste.
say sleep only forces animals to lie down calmly to avoid being discovered by arrested predators.
PET scans of the brain when people sleep normally In order to learn, we have to form connections, or synapses, between neurons in our brains.
these connections allow neurons to transmit signals to another neuron quickly and efficiently.
we store new memories in these networks.
In 2003, giulio Tononi and Chiara Cirelli, two biologists at the University of Wisconsin-Madison, suggested that our brain circuits became "very noisy" as daytime synapses formed in large numbers.
point out that when we sleep, our brains trim those synapses in the noise to send signals.
years, Tononi, Silelli, and other researchers found a wealth of circumstantial evidence to support this so-called synological stability hypothesis.
, for example, they found that neurons were able to trim their synapses.
laboratory experiments on stacked neurons, scientists applied drugs to them to cause them to grow extra synapses.
, those neurons trimmed some of the newly produced synapses.
other evidence comes from radio waves from the brain.
during deep sleep, brain waves decrease.
and Silelli believe that synapses are causing this change.
ago, Tononi and Silelli were given the opportunity to test their theories by observing the synapses themselves.
they got a slicer for brain tissue, which they used to cut brain flakes from the brains of mice.
De Vivo, an assistant scientist at the two-person lab, led a difficult study of brain tissue taken from mice, some awake and some sleeping.
and colleagues determined the size and shape of a total of 6,920 synapses.
found that sleeping mice had 18 percent smaller synapses in their brains than awakened mice.
" change is so big that it's amazing.
," Tononi said.
study was led by Graham H. Dilling, a postdoctoral fellow at Johns Hopkins University.
and colleagues are exploring the synhapological state hypothesis by studying proteins in the brains of mice.
"I'm really going to look at it in terms of the specifics," he said.
," Dilling said.
in an experiment, Dilling and colleagues created a tiny window to observe what was happening in the mice's brains.
, they added a chemical to brighten the surface protein on the brain synapses.
through this tiny window, they found that the amount of surface protein decreased during sleep in mice.
that's exactly what you expect when synapses decrease.
and colleagues then sought to explore the molecular causes of the change.
found that at night, hundreds of proteins increase or decrease within the synapses.
one of the proteins that stands out is Homer 1A.
in previous experiments on petri dish neurons, Homer1A has been shown to be important for synhap pruning.
wanted to know if it was important in sleep.
to find out, they specialized in mice that were genetically modified to produce the Homer1A protein.
mice sleep like normal mice, but their synapses don't change their proteins like normal mice do.
study by Pedrin, suggests that sleep drives neurons to produce Homer1A, which causes it to be transmitted to synapses of neurons.
and when the mice went to sleep, Homer1A activated the synth trimming mechanism.
to understand how this synactic pruning mechanism affects learning, the scientists tested the memories of ordinary mice.
put the mice in a room, and in the room, such as an area through the door, they were subjected to a mild electric shock.
, scientists injected a chemical into the brains of some mice.
have shown that the chemical prevents petri dish neurons from trimming their synapses.
, the scientists put all the mice back in the room they had been in before.
group of mice were too scared to move for much of the day because they recalled being electrocuted.
when the researchers put the mice in different rooms, they found a big difference.
mice would sniff curiously around.
mice that had been injected with chemicals and were unable to trim their brain synapses during sleep were once again unable to move.
that the mice injected with the chemicals could not remember which room they were electrocuted in.
their memories eventually became confused because synth trimming was not performed at night.
and colleagues found in the experiment that synth pruning did not affect all neurons.
fifth of the synapses don't change at all.
these synapses may contain fixed memories that should not be interfered with.
"You can forget in a smart way."
," Tononi said.
, on the other hand, some researchers warn that the new findings do not clearly support the synapse stabilization hypothesis.
G. Frank, a sleep researcher at Washington State University in Washington, D.C., says it's hard to say whether changes in the brain at night are caused by sleep or by biological clocks.
" is a common problem in this area of research.
," he said.
Markus H. Schmidt of the Ohio Institute of Sleep Medicine says that while the brain may indeed trim synapses during sleep, he is skeptical that this is the main cause of sleep.
to the latest research, he said, "They do a good job, but the question is, is synth trimming a feature of sleep, or is it just a normal feature?" Schmidt points out that it's not just the brain, many organs seem to work differently during sleep.
, for example, the internal organs seem to produce a lot of new cells.
new findings should prompt researchers to study how current sleeping pills affect the brain, Said Tononi.
these drugs may help people sleep, they may also interfere with the synact trimming mechanisms needed to form memories.
" this medicine may actually be bad for you.
," Tononi said.
, sleeping pills may precisely target the molecules involved in sleep, ensuring that synapses are properly trimmed.
"Once you understand what's going on at the basic level, you know how to better provide sleep therapy."
," Tononi said.
source: NetEase Scientific.