The Nature Of Sleep

What is sleep exactly? Although we know that all creatures that live sleep, and although science has diligently studied sleep in many sleep laboratories around the world, sleep itself—and its by-product, dreams—remains something of a mystery.

As I mentioned, you spend about a third of your life sleeping. If you have a life span of seventy-five years, you’ll be asleep for twenty-five of those years. Imagine! Yet, despite the prevalence and common experience of sleep, only recently did science begin to understand what it is all about.

Although dreaming and its causes are still a matter for speculation, brain wave studies provide important information about sleep itself. In a normal night, a person passes through four different stages of sleep, identifiable by brain wave patterns, eye movements, and muscle tension.

In the first stage, the pattern of the brain waves goes from what is known as beta, or normal waking consciousness, to alpha, the first step into sleep. The beta phase is 13 to 26 cps (cycles per second, the speed of the oscillations in the brain wave cycle), during which you are awake and fully functioning, studying, working, socializing. The alpha phase is 8 to 13 cps, a state of deep relaxation during which you are still aware of your surroundings, whether with eyes open or closed. It is the precursor to sleep and the stage reached during light meditation. Alpha is the sort of somnolent state we might go into on a long train ride when we have been staring out the window at a monotonous landscape for hours and are lulled by boredom and inactivity.

During the alpha stage, heart and pulse rates slow down, blood pressure drops slightly, and so does temperature. Your muscles are in a relaxed condition and you experience mental “drifting.” Images described as hypnogogic may float through your mind, seemingly unrelated to anything or else variations of what you were thinking or doing just before going to bed. These hypnogogic images can be vivid, as if drug-induced. Sometimes these images are quite meaningful and may startle you back to the beta state. When this happens, you may experience your muscles jumping back to the ready-to-go stage, a common happening that is called the myoclonic jerk.

Stage three is called theta and is represented by 4 to 8 cps, the same rate you display during periods of intense daydreaming (when you can actually forget where you are) or deep meditation. This stage of abstractedness is sometimes called a brown study. In the theta state, you are neither fully awake nor fully asleep. Yet you are in a light slumber, and, if not disturbed, you will fall asleep. The brain wave pattern of theta is characterized by rapid bursts of brain activity. Sleep researchers believe that theta is truly a sleep state, but when disrupted out of this state many subjects report that they were not asleep but merely “thinking.”

Researchers believe that it is during the theta stage that most dreams occur.

Dreams are recognizable to an observer by what is called rapid eye movement, or REM. The eyeballs move back and forth like someone watching a tennis match under their closed lids. Researchers originally discovered REM by watching cats sleep, and if you observe either a cat or a person sleeping, you will notice their eyes moving back and forth. A cat or dog may twitch as if running, but during REM a human’s muscles are virtually paralyzed. The period of REM ordinarily lasts for several minutes at a time, switching on and off. If you awaken during a REM period, you will most likely remember your dreams easily and in great detail.

“Dreaming liberates perception, enlarging the scope of what can be perceived.”
Carlos Castaneda,
The Art of Dreaming

The last stage is delta; at 0 to 4 cps, it is the slowest and is evident during the deepest part of the sleep cycle. This is the state when you are totally out and even a ringing telephone or alarm clock may not wake you. Teens often experience this deepest level of sleep in the early morning hours, which is why they are often hard to wake up for school. Teens actually do better when allowed to sleep late: you function better, learn better, and generally feel better when you are able to “sleep yourself out.” It’s unfortunate that teens are often mandated an early rising time for school or even before-school activities, such as sports practice. It’s not only how much you sleep, apparently, but also when you get your sleep that counts.

People awakened from the delta stage of sleep will feel disoriented and only half awake, and they will want nothing more than to go back to sleep. If, for example, a need to visit the bathroom wakes you from a delta sleep, you may bump into the furniture or the walls, even though you know your way around. During delta, there are no eye movements. It is also the time that sleepwalking occurs. As most everyone knows, a sleepwalker can move around unerringly, as if awake, and should be left alone unless he or she is in danger. If not awakened, sleepwalkers almost always make their way back to bed without a problem, and when they do wake up they have no memory of their nighttime excursions.

An average complete sleep cycle lasts about three hours. For the first hour and a half of the cycle the sleeper moves from a waking state to light sleep to REM sleep to deep dreamless sleep. The cycle reverses itself in the second half, returning upward (so to speak) from the deep sleep of delta to the lighter theta- alpha stages. As brain activity rises, so do blood pressure, pulse, and temperature. In warm weather, you may be awakened by feeling hot as your body temperature returns to normal. This is always a clue that you are in the process of waking up, and it’s a good sign to be aware of so that you will focus on your dreams and be ready to take notes on them.

Every night you go through three or four complete sleep cycles of ninety minutes each. The first REM period of the night lasts five to ten minutes. During each cycle, the REM is repeated, lasting longer as the night progresses, while the time between the cycles gets shorter. Your last REM can be as long as an hour, and this is prime dreamtime with excellent chances for good recall of your dreams. What this means in practical terms is that, if you sleep for seven hours straight, half of your dreamtime will occur during the two hours before you wake up in the morning. An additional hour of sleep will give you an additional hour of dreaming! This is a powerful argument for getting to bed early enough to get eight hours of continuous sleep. Of course, these figures are based on laboratory averages and may not hold true for every person—you are an individual and will sleep and dream in your own way. I have found that I dream twice as much as the average reported by sleep studies, sometimes with less sleep than the average, sometimes with more.

None of these states of consciousness—beta, alpha, theta, delta—are foreign to us. We cycle through all four of them during the course of twenty-four hours, slipping in and out of them, mostly without noticing. For example, during normal beta wakefulness, you may drift off into a daydream or reverie, thinking about tonight’s date or tomorrow’s picnic, and enter the alpha phase for a while. The phone rings, or a friend speaks to you, and you snap back into the beta state.

Or you could be driving your car along a monotonous route with little to pay attention to and slip for a few moments into the theta phase (lots of people fall asleep at the wheel for a few seconds and then quickly recover) only to flip back into beta as you see a sharp curve up ahead or hear another car honking. Everyone has had the experience of “dropping off” for a couple of seconds during ordinary everyday activities (or, perhaps, lack of activity).

For those who want to pursue dream studies, it’s important to pay attention to these alpha-theta states. There is a twilight zone where you are neither asleep nor awake but are alert to slight disturbances. It’s here you may catch a dream as it is forming, and it is in this state that you are best able to give yourself instructions for remembering your dreams-to-come and for “programming” dreams to fulfill specific purposes.

Use the following exercise to track your own personal sleep patterns. Following the format given here, keep a record of your sleep habits for two weeks in order to prepare for the exercises throughout this book. You’ll find out a lot about your sleep needs, when you dream, and your level of recall. Over time, even from day to day, you may find differences that are worth noting. Then, if you want to continue the process, record your sleep habits in a separate notebook.