Where do we go during sleep? Physically, it’s wherever we rest our heads. But what about in our minds? Sometimes in the dark void of deep sleep, it seems like nowhere. On dream-filled nights spent traversing time and space, however, the explanation seems less simple. And this unknown nature of sleep and dreams is exactly why some of humanity’s greatest thinkers spent ample time trying to dissect and understand them.
The seventeenth century in particular was ripe with theories on human consciousness and how it relates to sleep. Two centuries later, the advent of psychoanalysis would further fuel the fires of this debate.
While some ideas have aged better than others, in the continued absence of definitive answers it’s still worth considering a variety of views. From Descartes to Carlin, here are six great thinkers' thoughts on the trips we take when we’re not awake.
The Metaphysical Proposition
In Discourse on the Method, Rene Descartes proclaimed his famous dictum “Cogito Ergo Sum," or “I think therefore I am.” Through this succinct statement — and, to the endless joy of two-bit philosophy students — Descartes laid out the basis of his philosophy. He postulated that our mind was a physical substance and as long as it contained thoughts, we were conscious. By Descartes’ logic, as soon as our mind went unoccupied, it would cease to exist. Naturally this thinking held great implications for sleep.
The main objection to Descartes’ theory, which came to be known as Cartesian Dualism, was that even in the deepest of sleeps, we had to remain conscious or risk (quite literally) losing our minds. If then we were in fact conscious during slumber, questioned Descartes critics, how could his philosophy account for the state of dreamless sleep?
In response, Descartes offered this somewhat weak rebuttal in Meditations on First Philosophy:
“So long as the mind is joined to the body, then in order for it to remember thoughts which it had in the past, it is necessary for some traces of them to be imprinted on the brain; it is by turning to these … that the mind remembers. So is it really surprising if the brain of … a man in a deep sleep, is unsuited to receive these traces?”
The Empirical Objection
The British philosopher John Locke was unimpressed with Descartes metaphysical musings regarding sleep. For Locke, any statements made about the mind and its contents were pure hypothetical conjecture, raising this critique in the second book of his Essay Concerning Human Understanding.
Ever the hard-wrought empiricist, Locke resented the idea of some high-falutin Frenchman dictating the terms of our minds at rest. Rather, Locke believed the best judge for understanding our sleeping thoughts was, well, ourselves. He maintained that most would attest to the experience of dreamless sleep as constituting a total break in communication.
Trapped though by his own need for evidence, Locke was willing to concede that he was unable to account for where our minds wandered during sleep:
“That the soul in a sleeping man should be this moment busy a thinking, and the next moment in a waking man not remember nor be able to recollect one jot of all those thoughts, is very hard to be conceived, and would need some better proof than bare assertion to make it be believed. For who can without any more ado, but being barely told so, imagine that the greatest part of men do, during all their lives, for several hours every day, think of something, which if they were asked, even in the middle of these thoughts, they could remember nothing at all of? Most men, I think, pass a great part of their sleep without dreaming.”
The Middle Ground
Entering the philosophical fray, arms outstretched to separate his dueling companions, was Gottfried Leibniz, who sought a synthesis of opinion on sleep.
The way Leibniz saw it, humans were constantly in motion. He proposed that even in the most restful of states, our bodies and minds were in the least, minutely active. In this sense Leibniz held both Cartesian and Lockean ideas in mind.
From Descartes's perspective, Leibniz was in agreement that the mind was always thinking regardless of our level of consciousness. However, Leibniz added the proviso that Locke too was correct in stating that no conscious thinking occurs during sleep. It was here where Leibniz critically added his own theory that not all thinking was conscious.
Leibniz thus introduced the idea that images and thoughts occurring during slumber were rather the product of our unconscious. More specifically, Leibniz proposed that instead of an on-off light switch, our conscious was closer to a dimmer, going from the bright conscious thoughts of wakefulness, to the dark unconscious recesses of deep sleep.
The Unconscious Can of Worms
Out of Leibniz’s views on slumber, a greater question arose: If minds were responsible for the nightly precipitate of our dreams, then where in hell did those thoughts originate from?
Enter father of psychoanalysis and symbolic phallic-mongerer, Dr. Sigmund Freud.
One of Freud’s patients — a woman named Irma — was sick. Despite Freud’s best attempts at treatment, Irma’s condition remained consistent and like the good Jewish gent he was, Freud was plagued with guilt. Fortunately Freud soon found his solution through a dream. Less fortunate for Irma was that rather than a cure, Freud had discovered the answer to his guilt.
In the dream, Freud envisioned examining Irma at a party. In classic dream logic fashion, Freud came to realize Irma’s condition was actually caused by a dirty syringe used by a different doctor, absolving Freud of his responsibility for Irma’s ailment. As opposed to reality, Freud’s dream represented one of his deepest desires and with it his theory was born.
Freud expanded on this theory through Interpretation of Dreams, setting out the psychoanalytic framework for how our dreams function as a form of wish-fulfillment. For Freud, Leibniz’s notion that our sleeping thoughts belong to the realm of our unconscious made a lot of sense. Freud’s logical leap forward was that the images and ideas that came to us during sleep represented our deepest repressed urges. In essence then for Freud, no matter how abstract the thoughts that came to us in dreams were, each held some deep symbolic meaning reflective of our true psyche.
The Freudian Flipside
Freud’s misogynist-inclined theories haven’t aged too well. Instead Freud’s greatest contribution to our understanding of sleep, like his philosophical forebears, is the foundational groundwork his ideas have laid. Sleep researcher Rosalind D. Cartwright, for example, has greatly benefitted from Freudian thought, bringing it more in line with modern thinking on sleep.
In her book, The Twenty-four Hour Mind: The Role of Sleep and Dreaming in Our Emotional Lives, Cartwright explains:
“Sleep is a busy time, interweaving streams of thought with emotional values attached, as they fit or challenge the organizational structure that represents our identity. One function of all this action, I believe, is to regulate disturbing emotion in order to keep it from disrupting our sleep and subsequent waking functioning.”
According to Cartwright, the sleeping mind is far less involved in sorting through Oedipal complexes as it is in processing new experiences related to previous memories. This offers one of the most holistic views of sleep as a sort of nightly therapy session where the conscious merges with the unconscious as we process the events of the day that was.
The Comical Realist
Until we can categorically prove the true function of sleep, our thoughts on this phenomena still remain somewhat in the realm of philosophy. For that reason alone, it’s worth turning to one of the great philosophers of modern times, stand-up comedian George Carlin.
In his book Brain Droppings, Carlin demonstrated true wisdom by describing just how inexplicable sleep really is:
“People say, 'I'm going to sleep now,' as if it were nothing. But it's really a bizarre activity. 'For the next several hours, while the sun is gone, I'm going to become unconscious, temporarily losing command over everything I know and understand. When the sun returns, I will resume my life.”
If you didn't know what sleep was, and you had only seen it in a science fiction movie, you would think it was weird and tell all your friends about the movie you'd seen.
They had these people, you know? And they would walk around all day and be OK? And then, once a day, usually after dark, they would lie down on these special platforms and become unconscious. They would stop functioning almost completely, except deep in their minds they would have adventures and experiences that were completely impossible in real life. As they lay there, completely vulnerable to their enemies, their only movements were to occasionally shift from one position to another; or, if one of the 'mind adventures' got too real, they would sit up and scream and be glad they weren't unconscious anymore. Then they would drink a lot of coffee.'
So, next time you see someone sleeping, make believe you're in a science fiction movie. And whisper, 'The creature is regenerating itself.”