KIDS: Why do wE Sleep ? and What happens if wE don't ?

Sleeping is the price we pay for having a brain and able to learn new things every day: confirmation in a four-year study done on mice.

By day the synapses, ie the contact points between the neurons, are strengthened by stimuli that increase their number and volume: we make new experiences, we accumulate memories and skills. At night, part of this tangle breaks down: the synapses become thinner by about 20%, the useless memories are eliminated and there is room for those of the day to come.

The confirmation of the fact that sleep is essential to "cleanse" in human memory comes from a four-year study published in Science . The research of Chiara Cirelli and Giulio Tononi, who deal with sleep research at the Wisconsin Center for Sleep and Consciousness (USA), supports the theory of synaptic homeostasis , according to which sleep would serve to maintain a functional balance between the synapses.

BRAKE REQUIRED

When a brain connection is repeatedly stimulated during waking, it strengthens and grows: that trace of memory is consolidated, but this expansion must be at some point balanced to avoid a saturation of possible memories. The disposal process can take place in sleep, when we pay less attention to the outside world.

COMPARISON

To measure changes in synapse size between sleep and wake, researchers resorted to a technique called 3D electron microscopy. For 4 years, they analyzed two areas of the cerebral cortex of a population of mice, reconstructing 6,920 synapses and measuring their size. The work was done on healthy or sleep-deprived animals, without the researchers knowing what they were working on (double blind).

OBVIOUS

At the end of the experimentation, when they compared the measurements to the number of hours of rest, the scientists saw that a sleep of 6-8 hours was able to reduce the size of the synapses by 18%, in both the analyzed areas and proportionally to the size of the connections.
The process involved 80% of the synapses and spared the largest, perhaps coinciding with the most stable memories. By transferring the subject to man, it would mean that every night trillions (trillions) of synapses are reduced by 20%, to leave white space for new memories.

What if you do not sleep enough

COLDS- Who sleeps less than 6 hours a night runs a risk four times greater than contracting a cold. Sleep would have a key role in the regulation of T cells, white blood cells fundamental for the immune response. The lack of rest affects, in the vulnerability to sickness, more stress.

OBESITY - Sleep deprivation alters the hormonal balance that regulates hunger stimulation, increasing appetite for particularly caloric foods. Several studies show that those who do not sleep as much as they should tend to prefer sweet, fat, processed, very salty or carbohydrate foods, and to leave out fruit, vegetables and dairy products. Other research shows an association between the habit of sleeping with the light on and the risk of being overweight.

MIGRAINE-A great classic of the following morning: a poor quality of sleep is linked to the onset of migraine (the chronic appearance of headaches, concentrated on one side of the skull).

INTESTINAL PROBLEMS-Lack of sleep also seems to increase the chances of developing chronic intestinal inflammatory diseases, such as Crohn's disease or ulcerative colitis; worsens the symptoms of acid reflux and puts you at risk of incurring episodes of colitis.

EYESIGHT PROBLEMS - The longer you are awake, the more likely you are to experience visual errors and hallucinations. Not only. The prolonged lack of sleep can compromise peripheral vision (and therefore restrict the visual field), diplopia (double vision of the same object) and, in general, visual weakness.

MEMORY LOSS - Sleep is a fundamental step in the process of consolidating the memories learned during the day. Also, a good night's sleep can make information that we can not remember when we're awake more easily accessible .

LEARNING PROBLEMS-Not only does sleep help settle memories; it is also essential to do "cleaning" between the synapses (the connections between neurons), eliminating the superfluous ones to make room for new traces. Our memory can not expand indefinitely: an adequate amount of sleep helps to get rid of useless memories, creating space for new information to learn.

MOOD SWINGS-Interruptions, noise, interference and unexpected events tend to give us more trouble if we have not slept much. And it's just the beginning. A chronic lack of sleep is also linked to a higher risk of psychotic symptoms, personality disorders and hallucinations.

LACK OF COORDINATION-Sleep well, but above all allow yourself a few hours of extra sleep in the morning, improves performance that requires motor coordination. In particular, this benefit is linked to the duration of the Stage 2 of sleep, a phase that is shortened in the case of early rising. A dancer, or a pianist who does not succeed in a task will probably get better performances, after a good night's sleep.

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