Although you are one of the lucky ones who, between closing your eyes at night and opening them hours later in the morning, only knows the joy of deep rest, we all know that both the mind and the body remain active while we sleep.
We not only dream but we snore, we talk, we laugh, we shout, we tuck ourselves in and we untuck ourselves, and we even kick, punch, settle and spin.
But even if you fall asleep in a camping bed of less than 65 cm. wide or in the 200 cms. From a super king, you’ll most likely get up where you went to bed, no matter how hectic your night.
Why is it that we don’t fall out of bed?
“It’s fascinating because we think that when we sleep we are completely disconnected from our surroundings, but no: if someone shouts nearby, you wake up,” Professor Russell Foster, from the University of Oxford, told BBC Crowd Science.
“Our bodies continue to collect information via our receptors.”
And there is a sense that definitely does not fall asleep.
“ANDIt’s almost like a sixth sense. It tends not to be as good when we’re kids – that’s why some fall out of bed – but it gets better with age.”
So we don’t “black out” when we fall asleep, particularly not the kind that prevents us from waking up dazed—and perhaps bruised—on the floor.
Sixth Sense?
In popular culture, the sixth sense is associated with extrasensory perception, clairvoyance, premonition, intuition, the ability to communicate with a world inhabited by angels and ghosts.
But scientists like Foster mean a less esoteric one.
It’s called proprioception and experts have known about it for more than a century.
Pioneering studies on it were carried out in the 19th century by some of the giants of neuroscience: Frenchman Claude Bernard, “one of the greatest of all scientists,” according to science historian I. Bernard Cohen; the Scottish anatomist Sir Charles Bell, whose “New Idea of the Anatomy of the Brain” (1811) has been called the “Magna Carta of Neurology”; and Sir Charles Sherrington, who won the Nobel Prize in Physiology/Medicine in 1932 and who coined the term proprioception.
What was not clearly known until the second decade of this millennium is how much we depended on it.
Do you want to see it in action?
Close your eyes, and then touch your right index finger to the tip of your left elbow.
Easy? How did you do it?
Somehow you knew where your fingertip was and you also knew the position of your left elbow.
What’s more, you could describe your entire body posture without having to see it.
That is proprioception: the awareness we have of where each part of our body is located in space.
Proprioception is possible thanks to neurophysiological signals of receptors in our muscles, tendons, joints, and skin that inform the brain about the current length and stretch of the muscles, joint rotation, local changes, and flexing of the skin.
This allows us to know in which direction our joints are moving, makes us aware of our posture and balance.
It is the sense that, for example, helps you regain balance when you lose it.
Although in that case there is another that also plays an important role.
Imagine that you are blindfolded and I lean forward slowly.
You will immediately feel that the position of your body was changing in relation to gravity.
That’s thanks to the fluid-filled vestibular system in the inner ear, which helps us maintain balance. That system also gives us our experience of acceleration through space and is linked to the eyes.
But those do not help much to avoid falling out of bed, because they are closed, so let’s not lose the course.
Let’s take it back by quoting the professor of kinesiology and neurology at Pennsylvania State University, USA, who wrote in The Conversation that proprioception is “a key component of our ‘Global Positioning System‘which is essential in our daily lives because we need to know where we are to move somewhere.
“Proprioception allows us to determine the position, speed and direction of each part of the body, whether we see it or not, and thus allows the brain to guide our movements.”
Thanks to this, when we are asleep, we can move freely, but without going beyond the borders of the bed.
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