10 things you need to know about sleep, part 2

Which animal sleeps the longest and how long can a man last without sleeping? Is it true that the Japanese never sleep and that when we wake up we are all taller? Here are five more curiosities about sleep: a challenge without excluding yawning.

5 things that perhaps we should know to sleep peacefully

6. The country where you sleep least

Japan is one of the countries where you sleep least in the world. It is not uncommon, however, to see men and women of all ages seemingly asleep in completely ordinary circumstances. Warning: they are not sleeping, they are making inemuri.

The literal translation of this term is to be present in sleep (nemuri means sleep; the prefix i- indicates being present) and is used to indicate the act of falling asleep on the spot, in whatever context one finds oneself, even - and above all - in public, without this causing embarrassment.

Those who let themselves go to these moments of pause are very likely to do so because they have literally consumed themselves with work: the inemuri would, therefore, be a sign of dedication and complete surrender to the frantic rhythms that Japanese society imposes. The particularity, however, is that, when the situation requires it, those who practice inemuri are able to return to their activities ... in the blink of an eye.

7.  Sleep oddities in the animal world

Even in the animal world there is no shortage of curious habits. There are those who spend most of the day sleeping: to digest the eucalyptus leaves of which it is greedy, the lazy koala sleeps between 20 and 22 hours; the sloth, equipped with strong claws thanks to which it remains anchored to the branches of the trees, rests almost 19 hours a day; like all bats, sleeps upside down even the brown vespertilium, which at night goes in search of food and for the remaining 18 hours you indulge in sleep.
Then there are those who, instead, sleep very little: elephants are content with only 2 hours a day, as well as giraffes, which from time to time during the day allow themselves to nap for a few minutes.

Some animals sleep mainly standing, others only moving, and then there are those who never sleep: dolphins and whales, in fact, have a particular ability, called alternate unihemispheric slow-wave sleep, which allows them to sleep with half their brains at a time, keeping the other half completely active and that senses the possibility to feel dangers and threats.

The idea of Bruce McAllister and Randy Garner was to break the record of absence of sleep, until then held by a dj from Honolulu, who remained awake for 260 hours in a row.

A baby sloth is sleeping

8. Sleep and height

Sleep makes us taller. In the morning we measure 0.5 cm more: this is because the intervertebral discs - those pads that are placed between the vertebrae of the spine and have the function of cushioning the pressure and, in general, the shocks that our column suffers during normal activities that we perform, making it possible to move - at night are not stimulated by weight and gravity and then return to their original shape.
A couple sleeps peacefully by train

9. Animal hibernation

After a long preparation, which took place between the summer months and autumn, with the arrival of the coldest season, many animals - mammals, reptiles, birds and amphibians - begin to hibernate: a long sleep, or rather, a state of dormancy is necessary to overcome the difficult environmental conditions.

During this period, the animals reduce their vital activities to a minimum: blood pressure drops, the heart rate decreases to a few beats per minute, breathing becomes slow, body temperature drops and metabolism is drastically reduced.

The marmot lives in the prairies but hibernates for long months

The Guinness World Records has also stopped validating primates on sleep deprivation, because of the risk of damage to the health of participants

Among the species which hold the record of the longest hibernation, there is not, as one might think, the famous dormouse, but the Alaskan marmot and the Arctic squirrel, which sleep almost 8-9 months a year.

If the winter hibernation is known to most people, perhaps, however, not everyone knows that there are animals going to summer: a sort of reverse hibernation which allows fishes, amphibians, reptilians and some small mammals to survive in the desert regions, where the too much heat and the prolonged lack of water would otherwise make life difficult.

10. Record of absence from sleep

The sleepless man. It was the end of 1963 when, almost for fun, two young American students, Bruce McAllister and Randy Garner, started an experiment that quickly attracted the attention of the entire country. The idea was to break the record of absence of sleep, until then held by a dj from Honolulu, who was awake for 260 hours in a row.
Between the two, after throwing a coin, Randy was the chosen one for the test, and Bruce, together with his friend Joe Marciano, took charge of monitoring the experiment. Soon a researcher from Stanford University, William Dement, interested in sleep studies, joined the team. He had read about the experiment in a local San Diego newspaper, supporting the boys mainly from a medical point of view.
Arctic squirrel climbing a tree
Randy, who remained in good shape throughout the period, however, experienced short-term memory and concentration problems, sudden mood swings, paranoia and hallucinations, as well as hypersensitivity to strong smells and tastes.

After 264 hours without sleep (the equivalent of 11 days and 25 minutes), Randy Garner could finally close his eyes: he slept 14 hours in a row and then another 10 and a half, and then resumed his activities regularly, without recording - in the weeks and months that followed - significant physical or psychological effects.

Over the years Gardner's record has been broken several times, but his case remains relevant because it is the only one that has been studied and monitored in detail. Guinness World Records has also stopped validating records of this type, because of the risk of damage to the health of participants.

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