The Secret Life of Sleep

Kat Duff

• Publisher: Atria Books/Beyond Words
• Year: 2014
• ISBN:
  9781476753287
• Topic: Medicina
• Subtopic: Medicina del sueño

Unlock the astonishing facts, myths, and benefits of one of the most endangered human resources—sleep. It has become increasingly clear that our sleep shapes who we are as much as, if not more than, we shape it. While most sleep research hasn't ven­tured far beyond research labs and treatment clinics, The Secret Life of Sleep taps into the enormous reservoir of human experiences to illuminate the complexities of a world where sleep has become a dwindling resource. With a sense of infectious curiosity, award winning author Kat Duff mixes cutting-edge research with insightful narratives, surpris­ing insights, and timely questions to help us better understand what we're losing before it's too late. The Secret Life of Sleep tackles the full breadth of what sleep means to people the world over. Embark on an exploration of what lies behind and beyond our eyelids when we surrender to the secret life of sleep.

1

WHEN THE SANDMAN COMES: FALLING ASLEEP

A photographer friend of mine once invited me along on an overnight shoot in an old mining town/ski resort in the mountains nearby. It was a chance to get away, see the fall colors, and spend a night in a historic hotel during the quiet off-season, so I accepted. Unbeknownst to us, however, it was the three-day weekend of Oktoberfest, when Texas universities empty their charges onto the streets of this little town, and for much of the night, young men hold races shouldering full kegs of beer to the whooping and hollering of their friends. The room we were given was right over the Lost Love bar, which had a live band playing that night, and across the street from the Bull O’ the Woods Saloon, where the kegs were enjoyed.

There have been times in my life when I could fall asleep anywhere, anytime; but those days are long past, and this particular night gave me ample opportunity to employ all the tricks I have learned over the years to help myself fall asleep. I pulled the curtains shut to block out the street light, plugged in the ear buds of my iPod, stretched out under a warm comforter in the cool air from a cracked window, avoided thinking about aggravating topics—and didn’t fall asleep. Finally, I got up, found a crime novel abandoned in a lounge upstairs, and settled down to read the night through. Before long, I had fallen asleep, only to be jolted awake by the sound of my book hitting the floor. When it happened a second time, I decided to try my bed again.

As I padded down the creaky wooden stairs in my socks, it occurred to me that this was the perfect opportunity to observe myself falling asleep and catch as many details of the transition as I could. I slid into bed noting the heaviness in my limbs, my repeated yawning, the tears that slid out the corners of my eyes, my twisting and turning to find the right position under the covers, the flickering of thought-images in that interior space behind my eyelids—and woke up when the band stopped playing at 2:00 AM. I turned over and tried again, this time noticing the sluggishness of my body when I shifted position, my dreamy dimwittedness, a curious, uncaring confusion as to where or who I was .  .  . until I was jolted awake by another howl from the street below.

The Sleep Switch

A traditional West African Ashanti tale describes sleep as “The One You Don’t See Coming”—the thief you will never be able to catch.¹ Much as we may try, people simply cannot observe themselves in the exact instant of falling asleep. An old German rhyme portrays the effort to catch sleep coming:

I would like to know how one falls asleep

Over and over I press myself in the pillow

And thereby think: “Now I will pay attention.”

But before I have really reflected,

It is already morning,

And I have again awakened.²

It is as if a curtain of unconsciousness is swung across the stage, making it impossible to see—or remember—what happens. The ancient Greeks conceptualized this swipe of forgetting as the river of oblivion (Lethe) that circles the cave of sleep (Hypnos) in the underworld. They said that the murmuring waters of Lethe made people drowsy and washed their memories away when they came close to sleep, for in this ancient understanding, sleep required forgetting ourselves in order to enter its inner sanctum.

In 2001, sleep researcher Clifford B. Saper and his colleagues at Harvard University identified a cluster of neurons in the hypothalamus deep inside the brain that triggers sleep onset. This cluster, which they termed a sleep switch, secretes chemicals that effectively shut down wakefulness, including the capacity to be aware of what is happening in the moment, while simultaneously inducing sleep.³ This switch may be the biological equivalent of the River Lethe.

When we are awake, our brains produce and store a chemical called adenosine triphosphate (ATP) to fuel cell activity. However, as ATP accumulates over the day, it begins to slow down brain activity, making us feel progressively more tired and drowsy. Eventually, with the contribution of other sleep-promoting factors too numerous to mention here, that system-wide state shift we call sleep takes over. As anyone who has pulled an all-nighter can attest, the longer we have been awake previously, the longer and deeper we will sleep to make up for the loss. Scientists propose that a contra-parallel process occurs while we sleep; other chemicals slowly accumulate until we cannot help but wake up and stay awake. It is a homeostatic mechanism that is independent of the cycles of day and night.

Even though we may spend hours approaching sleep, with attending changes in body temperature, brain wave patterns, hormones, and neurotransmitters, the transition from one state to another seems to occur instantly and completely. Noting that sleeping and waking modes appear to be mutually exclusive, Saper and his colleagues theorized that the switch operates likes an on-off, flip-flop toggle, meaning that we are either awake or asleep without much middle ground. The light goes out, as people say, when the switch is flipped, and our brain waves burst into the large oscillations we experience as unconsciousness.

People have often wondered and imagined what flips the switch. In Greek mythology, the god of sleep, Hypnos, taps us with his wand or brushes us with his wings to put us to sleep. In traditional Blackfoot lore, it is a butterfly. In popular European children’s stories, the Sandman sprinkles sand or dust on our closed eyes. Whichever way, it takes but a moment, a simple tap, brush, or sprinkle. The experience reminds me of jumping off the high dive—the long climb up the ladder, the tiptoeing back and forth on the board in that familiar push and pull of wanting to jump and being afraid to jump, until the moment seizes us, we leave solid footing, and—a split second later—splash into another world, a wild and watery reality.

Threshold Consciousness

As we wind down and veer toward sleep, we travel through a transitional state called hypnagogia, named after Hypnos. The word literally translates as “sleep driver.” There’s a parallel transitional state, called hypnopompia, when we wake up. Most of the time, we zip through these states so quickly that we miss them altogether. But occasionally, we pause, as if waiting for the stoplight to turn. During hypnagogia, clusters of neurons take turns shutting down, and sleep creeps over us. Our brain waves slow to a trance-like rhythm, and our attention drifts. When I have engaged in a repetitive task during the day, like playing ping-pong or solitaire, I often see the balls or cards moving into place as soon as I close my eyes. It is called the Tetris effect, after the video game. The effect can also take an audio or kinesthetic form, like feeling the rocking motion of waves after a day of snorkeling.

Hypnagogia and hypnopompia involve more than reliving sensations from daytime activities. People report fleeting visions of geometric patterns; sparks of light or splashes of color; and roaring, hissing, or clanging sounds. Faces may appear with friendly, threatening, or comical expressions. Landscapes unfurl themselves, revealing familiar and otherworldly realms. Sometimes snatches of songs or conversations float by. Virginia Woolf described it well in her novel To the Lighthouse:

As she lost consciousness of outer things  .  .  .  her mind kept throwing up from its depths, scenes, and names, and sayings, and memories, and ideas, like a fountain spurting  .  .  .

Occasionally, there is the sensation of floating, spinning, or getting bigger or smaller. It is a bizarre reality we slide through between waking and sleeping. The Spanish poet Federico García Lorca once spoke of fairies appearing when mothers sing lullabies to their babies and described seeing one himself once when he was visiting a cousin as a child. Vladimir Nabokov wrote in his autobiography that he would often “become aware of .  .  . a neutral, detached anonymous voice which I catch saying words of no importance to me whatever—an English or Russian sentence” just before falling asleep. A friend of mine admitted that she sometimes feels herself swelling up like a balloon until she is as big as the room and then shrinking down to the size of a pea, repeatedly, until she loses all awareness.

Sometimes people startle themselves (and their bedmates) with a massive, involuntary jerk. The scientific name for this phenomenon is myoclonic kick, though it is more commonly known as a sleep start. While it appears to be a primitive reflex generated by the brain stem, no one really knows why we startle like this on the cusp of sleep. Some theorize it is because our brains mistakenly confuse the sudden release of muscle tension, especially among the muscle groups that resist gravity, with a frightening free fall and jerk to stop it, as if grabbing for a branch when tumbling from a tree. Others propose it is left over from the evolutionary need to keep watch for danger, waking us whenever we start to slip off.

Whatever the case, the sensation of dropping suddenly is so strong, people often have split-second dreams of falling, whether it is tripping while running, slipping on ice, tumbling down stairs, or plunging from a precipice. Neurologist Oliver Sacks finds these split-second dreams, which he prefers to call hallucinations, particularly fascinating because they demonstrate how quickly our minds can work to invent a narrative to explain a sensation. In the moment, it seems that the dream has triggered the startle, but it is probably the other way around. Sacks proposes that a “preconscious perception” of the jerk prompts “an elaborate restructuring of time” to provide a story for the event.⁴ If he is right, and I suspect he is, our startle dreams are actually cover stories, something like the tales kids spin to explain why the cookies are gone, only more convincing.

These tripping, slipping, tumbling, and plunging dream stories are so common, and so convincing, they have made it into more than a few lullabies. My favorite is the popular “Rock-a-Bye Baby,” which has the baby blowing in the wind and falling “cradle and all” at the end. I have always wondered why a lullaby intended to lull an infant to sleep would include such frightening imagery; it seems a cruel thing to give a child heading into the land of Nod. Now I understand. Bedtime is falling time, and these lullabies prepare us for the hallucinations of falling that so often attend the slip into sleep.

Coinciding with the World

For thousands of years, this surreal trance-like state before sleep has been recognized as a place of insight, inspiration, and telepathy. As psychologist Deirdre Barrett documented in her book, The Committee of Sleep,⁵ nineteenth-century German chemist August Kekulé credited his discovery of the ringed structure of benzene to a hypnagogic vision of circling snakes he had one night while dozing in front of a fire. Eighteenth-century scientist and philosopher Emanuel Swedenborg developed a method for inducing and exploring these states, during which he claimed to have traveled to heaven, hell, and other planets. Salvador Dalí drew inspiration for his paintings from the bizarre imagery of sleep states and recommended eating sea urchins for the best results. Thomas Edison cultivated hypnagogic states to get ideas for new inventions. He would take short naps in the middle of the day while sitting in a chair and holding steel balls in his hands. The moment his muscles relaxed on the brink of sleep, the balls dropped into pie pans, whose clanging woke him instantly—sometimes with a new approach to an old problem.

In 1906, psychoanalyst Herbert Silberer conducted what he called introspective experiments into hypnagogic imagery while falling asleep.⁶ To his astonishment, Silberer noted that the images that appeared often related to what he had just been doing. One day, when he tired of trying to improve an awkward passage in an essay he was writing, Silberer closed his eyes and saw himself planing a piece of wood, refining and finishing the shape. On another occasion, after puzzling over something he later admitted was forcing “a problem into a preconceived scheme,” he saw himself trying to press a jack-in-the-box back into its box. Over time, Silberer became adept at watching his thoughts transform into a loose array of images and feelings, what Sigmund Freud called primary process thinking. His psychoanalytic orientation gave him a framework for understanding that transformation, making the experience of falling into imagery a familiar, benign, and intriguing one.

However, many are surprised, confused, and even disturbed by the bizarre phenomena that arise at the edge of sleep. The sights, sounds, and sensations can feel so foreign, it is hard to believe they come from inside us, if they do. I have occasionally questioned whether some elements slip in from outside, and the following event made me wonder even more.

I was staying with friends in New Orleans in the midst of a cross-country trip. Dropping off to sleep, I saw a stark black-and-white image of dead cats strewn about an empty street at night. I bolted upright, calmed myself down, and fell back asleep. It happened again, this time with a slightly different view. Every time I went back to sleep that night, there were more dead cats, until I finally got out of bed. Having recently changed my nickname from Kitty to Kat, I thought the visions were telling me that I had died in some way. I poured myself a cup of tea, sat down at the kitchen table, and pondered the implications until dawn. A few hours later, I received a phone call from the friend who was taking care of my cat, FB, while I was away. She told me that she had found FB’s body in the street that morning. FB had been run over during the night.

The French philosopher Gaston Bachelard once wrote: “Sleep opens within us an inn for phantoms.” While it is not clear whether his phantoms come from within or without the sleeper, he is assured of their fundamental otherness, for he added: “The repose of the night does not belong to us. It is not the possession of our being.” The apparition of dead cats that kept intruding upon my sleep that night in New Orleans seems connected—at least in time—to FB’s demise in that country lane in western Massachusetts. How that specter found me, and got my attention, is beyond my understanding.

Perhaps there is something about these transitional states that enables us to tune in to dimensions of reality that are ordinarily inaccessible. Psychologist Simon Sherwood concluded that these times are “more conducive to telepathy” in his meta-analysis of relevant studies.⁷ After all, the hypnagogic state is known to be an impressionable one. Hypnotists regularly induce it in order to circumvent the conscious beliefs of their clients, just as the artists, inventors, and psychologists mentioned above looked to these states to attain insights only available outside their ordinary thinking. Andreas Mavromatis, who published in 1987 what remains the most comprehensive book on hypnagogic experiences, noted that people who share sleeping spaces sometimes see the same images as they drop off, as if the visions were silently passed around in the permeability of near sleep.⁸ The French philosopher Jean-Luc Nancy may have explained it best when he described a simultaneity that occurs when falling asleep: “I coincide with the world.”⁹

When we lie down, close our eyes, and begin to drift off, we let our guards down and allow ourselves to receive what comes without filtering out the crazy pieces. Our carefully constructed notions of ourselves, of where we end and the world begins, dissolve without our knowing. Startling bits of unknown information may well slip into our minds before the waters of Lethe wash everything away.

2

OPENING THE INN FOR PHANTOMS: SURRENDERING TO SLEEP

One night years ago, when I was living in a communal household in Austin, Texas, one of my housemates ran into my room, screaming that she had just broken free fro...