Evolution endowed us, like other creatures, with sleep that is malleable in its timing and readily interruptible, so it can be subordinated to higher priorities.
Around 350 B.C., Aristotle wrote an essay, “On Sleep and Sleeplessness,” wondering just what we were doing and why. For the next 2,300 years no one had a good answer.
Most of what we know about sleep has only been discovered in the last 25 years.
Maybe, we’ve been asking the wrong question about sleep, ever since Aristotle.
The real wonder isn’t why we sleep. It’s why, with such an incredible alternative available, do we bother to stay awake?
Sleep is ancient, its original and universal function, is not about organizing memories or promoting learning but more about the preservation of life itself.
The problem is that in the modern world, our ancient, innate wake-up call is constantly triggered by non–life-threatening situations.
Every animal, without exception, exhibits at least a primitive form of sleep.
Giraffes sleep less than five. Horses typically sleep part of the night standing up and part lying down. Dolphins sleep one hemisphere at a time—half the brain sleeps while the other half is awake, allowing them to swim continuously. Great frigate birds can nap while gliding, and other birds may do the same. Nurse sharks rest in a pile on the ocean floor. Cockroaches lower their antennae while napping, and they’re also sensitive to caffeine.
While we humans nod off into a surreal descent of sleep, into an alternative world, our heart rate slows and our core temperature drops. Any remaining awareness of the external environment disappears.
Our sleep-wake pattern is a central feature of human biology—an adaptation to life on a spinning planet.
The average human today sleeps less than seven hours a night, about two hours less than a century ago.
The floodlit chaos of our waking life of mobile screens are now overworking our neurons, (some 86 billion of them, the cells that form the World Wide Web of the brain, communicating with each other via electrical and chemical signals) and has made sleep deprivation a lifestyle, overloading the sleeping brain to be able to consolidate the information that’s been collected during our awaking hours.
What makes us sleepy?
Everyone needs sleep, but its biological purpose remains a mystery.
Sleep affects almost every type of tissue and system in the body – from the brain, heart, and lungs to metabolism, immune function, mood, and disease resistance.
Many mysteries remain about the association between sleep and health problems. Does the lack of sleep lead to certain disorders, or do certain diseases cause a lack of sleep? These, and many other questions about sleep, represent the frontier of sleep research, like what effect do different foods have on sleep.
The strength of one’s nightly spindles, some experts have suggested, might even be a predictor of general intelligence.
Sleep literally makes connections you might never have consciously formed, an idea we’ve all intuitively realized that it may be more essential to us than food.
We have yet to find a truly sleepless creature however there’s is only one species that has been called ‘biologically immortal. Jellyfish do not breath and there are plenty of other unusually long-lived species that seem to defy the passing of time.
We all love life and we wish to live as long as possible, but in spite of this we sacrifice about 1/4 of more of our lives to sleeping.
James Webb can see the origins of the universe – something our minds can hardly begin to grasp as we sleep into the future.
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