Every one of us has a mysterious double life.
For about two thirds of the time we are conscious beings, thinking about the world within and without, and negotiating our ways through the obstacles of life. For the other one third of the time we are nearly lifeless lumps of flesh, unconscious to everything but our own fantasies, as we lie flat in bed asleep. We all know that sleep is important for health. But for an activity that consumes about 8 hours of everyday of life, surprisingly little is thought about the act of sleeping, or the way our culture teaches us to sleep. Sleep behavior, like all human activities, is defined by our culture.
Sometimes, the practices taught by our culture can impact on the way our bodies function. As medical anthropologists, we research ways our cultural practices may be affecting our health. And we have found that the way we have been trained to sleep may be one of the most important causes of various diseases plaguing our society.
Of course, when you consider the culture of sleeping, it includes such isues as the length of time to sleep, and time of day for sleep. Do you take frequent naps or do you sleep 8 hours straight? Do you sleep at night or during the day?
Other issues concern sleepwear. Do you sleep nude, or with pajamas or lingerie? Do you sleep in your underwear? Should the sheets be natural fabrics, such as cotton or silk, or is polyester okay? What about the detergent and fabric softeners used in the sheets, pillow case, and pj's?
Should you eat before you sleep? What is the impact of watching television before sleep? Should you take sleeping pills to help you sleep?
These are some of the culturally defined issues that help determine how we sleep, all of which may have some potential impact on health. However, there is one cultural issue that tops the list of importance, and which may greatly determine your health status. It has to do with your sleep position. Are you sleeping on a firm, flat bed, face down, with your nose and eye compressed against the bed and pillow? Or are you on your back with your head slightly elevated, as is the case for many native cultures that use hammocks or other non-flat surfaces for sleep?
The reason we ask this last question is because the circulation to the head and brain is completely related to your body position when sleeping.
We all have had a time of experiencing dizziness or lightheadedness when getting out of bed too quickly. This effect is called orthostatic hypotension, and results from the fact that blood pressure falls when you lie down, and sudden raising of the head may temporarily deprive the brain of sufficient blood pressure, resulting in the dizziness or lightheadedness. The blood pressure soon rises, increasing the blood supply to the brain, as you feel normal again.
This phenomenon shows that the body's position, relative to gravity, influences head and brain circulation. You can also demonstrate this by doing a head stand, which many yoga practitioners do daily. Intracranial pressure rises dramatically, as blood rushes to the head, which becomes beet red, and the neck veins swell out, as blood pools in the venous system.
But apart from these examples, very little, if anything, is mentioned in medical physiology textbooks about gravity and its impact on circulation. Yet, you cannot fully understand brain circulation without considering gravity.
The effect of gravity on brain circulation is purely mechanical, and relates to the position of the head relative to the pumping heart. When we are standing up, the head is above the heart, so blood must pump against the force of gravity -- from the heart to the brain -- lowering the effective pressure with which the arterial blood is delivered to the brain. Meanwhile, drainage of blood from the brain to the heart is facilitated by the pull of gravity.
In contrast, when we lie down and are horizontal, the heart and head are now on the same plane. This eliminates the effects of gravity on brain circulation. Blood from the heart pumps powerfully into the head without gravity's resistance, increasing intracranial pressure. And blood returning from the brain to the heart must do so without gravity's assistance, causing a back-up of blood in the brain.
Essentially, intracranial pressure increases, and overall brain circulation diminishes, when you are lying flat compared to standing up.
Of course, the body is intelligent and has mechanisms for controlling brain pressure under different gravity situations. When the brain gets pressurized from lying down, there are various pressure receptors in the head and neck designed to lower blood pressure, thereby preventing too much brain pressure and the possibility of blowing a blood vessel or creating a cerebral aneurysm. This is why blood pressure is lower when we are sleeping, and horizontal.
But these brain mechanisms for adjusting pressure have their limits. As we go through the day in a vertical position, gravity relentlessly pulls our body's fluids downwards, which is why many people have swollen feet and ankles by day's end. Once we lie down, the gravity effect is lost, as fluid leaves the legs and returns to the head. So despite our brains normal defense mechanisms, throughout the night intracranial pressure increases and is highest in the morning, after hours of lying flat, and lowest at the end of the day, after hours of being vertical.
What happens when intracranial pressure is high from long periods of lying flat? The increased arterial pressure causes extra cerebral spinal fluid to form in the brain's ventricles, increasing intracranial fluid pressure. The ventricles swell and the cells of the brain become bathed in excess fluid, essentially causing brain edema. This edema would lower the available oxygen and sugar for brain cells. The lack of gravity assisted drainage from the brain would cause a back-up of blood in the venous system and collecting sinuses in the brain. The brain's circulation would become relatively stagnant, as the only force moving blood through would be the pushing force of the arterial pressure (which is greatly reduced after going through the cerebral circulation) and the sucking force of the heart's right atrium. And in addition to the brain swelling under the pressure, the eyes, ears, face, sinuses, gums -- the entire head -- will become pressurized and the tissues congested with fluid!
There is one field of medicine that avidly studies this effect of gravity on physiology. That sub-specialty is Space Medicine. Astronauts in space are in a zero-gravity field, and it is known that this causes blood to shift to the head and brain, causing increased brain pressure and accompanying migraines, glaucoma, Meniere's disease, and other problems associated with a pressurized, congested brain. To study the negative effects of zero-gravity here on Earth, these space scientists have people lie down flat! However, since medicine is so wide a field, with sub-specialists learning more and more about less and less, there is little exchange of ideas between space medicine and Earth-bound medicine. Otherwise, someone would have realized that lying flat is what we do when we sleep. If it causes problems for astronauts, then couldn't it cause problems for everyone else?
We found out about this Space research while we performed our own research into sleep positions as a possible cause of migraines. We hypothesized that sleeping too flat for too long each night could lead to brain pressure and fluid accumulation (edema) within the brain tissue, with associated hypoxia and hypoglycemia. The brain cannot function well without proper amounts of oxygen or sugar, and this condition would be at its worst in the morning, which is when most migraines occur.
While migraines have been thought of as a pathological phenomenon, it is also possible that the migraine is the brain's defense mechanism to receive new blood along with sugar and oxygen. After all, the only way the brain can get what it needs is from the bloodstream, and during a migraine arteries to the head open up and send blood with force throughout the brain. Perhaps, we reasoned, the migraine is a type of emergency "brain flush", replacing old blood with new. If so, could we prevent migraines by having migraine sufferers sleep with their heads slightly elevated?
We tested our theory by having about 100 volunteer migraineurs sleep with the heads of their beds elevated, from 10-30 degrees. Head elevation, we theorized, would improve the brain circulation by providing some gravity assistance to drainage. Interestingly, we found that Space Medicine researchers discovered that brain circulation (and heart pumping) is optimal at a 30-degree head of bed elevation.
To our amazement, we found that the majority of the migraineurs in our study experienced relief by this simple sleep position change! Many had no new migraines, after being migraine sufferers for 30 or more years! The results were very fast, within a few days. And there were very interesting side effects, too. Our volunteers woke up more alert. Morning sinus congestion was significantly reduced for most people. Some reported that they no longer had certain allergies. Could we have discovered the real purpose and cause of migraines?
The implications of these findings were, frankly, astounding to us. So many diseases are related to increased brain pressure of "unknown" cause. Sleep position was never studied as the cause of this increased pressure. The implications go far beyond the prevention and treatment of migraines. Any condition that is related to brain pressure, and that is usually worse in the morning after a night of horizontal time, can be potentially related to this gravity and sleep position issue.
Keep in mind that the brain is the central nervous system controlling and modifying all bodily functions. If certain centers of the brain are congested and pressurized daily by sleeping too flat for long hours, those centers can malfunction. Depending on the way a person sleeps, the idiosyncrasies of their brain circulation, and other variables, different people might experience this brain pressure differently. For some, the respiratory centers of the hypothalamus might be particularly congested, resulting in Sudden Infant Death Syndrome (which has been associated with head and body position while sleeping), sleep apnea, or even asthma. Sleep apnea has been shown to be treatable with changes in sleep position.
Strokes are clearly associated with brain pressure, and usually occur at night or in the early morning, while sleeping. This is when brain pressure is highest.
Glaucoma is clearly caused by this mechanism. It is already known that eye pressure increases when the head is down, and decreases when the head is up. It is essential to note the head position when taking eye pressure readings because of this sensitive relationship between intraocular pressure and head position. Eye pressure is also highest in the early morning. Elevating the head while sleeping should be routine for glaucoma treatment and prevention.
Baggy eyes and sinus congestion seem to be related to head pressure. Just as the brain gets extra pressure when lying down, the head and face are pressurized, too. People with these problems usually find immediate relief by sleeping elevated 10-30 degrees.
Alzheimer's disease, we believe, might be the end disease caused by chronic brain congestion and pressure from flat sleeping. The cerebral ventricles of the Alzheimer's brain are expanded, suggesting a history of ventricular pressure, and generalized lesions along the ventricles may indicate areas of brain tissue that have deteriorated from this chronic pressure. Other research has already shown Alzheimer's is associated with increased brain pressure, but the cause has been considered unknown, as is the case with almost all brain pressure problems.
It should be noted that the blood-brain barrier cannot function properly when pressurized. Excessive intracranial pressure can cause leaks in this barrier by expanding the basement membrane, allowing heavy metals, e.g., aluminum and mercury, as well as viruses and bacteria, to enter the brain that would have otherwise been excluded. This may be why heavy metals have been associated with certain brain problems, such as Alzheimer's.
Attention Deficit Hyperactivity Disorder is also known to be associated with congestion of the "impulse center" within the brain that helps control behavior. We found several children with ADHD experience profound improvement of self control by elevating their heads while sleeping.
In addition to head position relative to gravity, we also have found side or belly sleeping can create problems. For example, we found several cases of carpel tunnel syndrome related to sleeping on the hands or wrists, and shoulder pain from sleeping on the side. And keep in mind that head pressure increases, and drainage diminishes, when the head is rotated to the side. Sleeping on the back avoids compression of limbs and internal organs.
It is also interesting to note that patients with asymmetrical problems will typically be worse on the side they sleep on. For example, eye pathology will be worse in the eye on the side of the face that is slept on most. Ear infections will be worse on the "down" ear. You can also tell the side a person sleeps on by observing the shape of the nose. Apart from injuries, the nose should be symmetrical, but becomes curved away from the pillow because of sleeping on the side of the face and pressing on the nose for hours each night. The nose will point away from the side that is most slept on.
Men should be told that side sleeping may result in testicular compression and possible dysfunction. And women who sleep on their sides or stomachs subject their breasts to compression and impaired circulation. Side sleepers may have more breast trouble on the side they sleep on.
We should forewarn the practitioner, however, that, while the effect of elevating the head while sleeping will be dramatic and transformative for many patients and should be considered essential to disease prevention strategies, the fact is that many people resist changing their sleep behaviors. They have been conditioned to sleep a certain way since birth. And even when they want to change their sleep position, it's difficult to ensure compliance when the subject is unconscious! It takes tremendous will power to alter sleep behavior. But it is well worth the trouble, as people usually see within a week of sleeping elevated.
We found the best methods for head elevation include using more pillows, using a foam wedge, placing blocks under the legs of the bed frame at the head of the bed, or using an adjustable bed. While the ideal position is with the head from 10-30 degrees elevated, 10 degrees elevation is fine to start with. The legs should be slightly elevated, too, and the person should try to stay on his or her back as much as possible. The ideal position is one you would be in if leaning back in a recliner chair. (Recliners would be fine to use, too, but they usually give poor lower back support.) Also, be aware that some people will find one degree of elevation more comfortable than another. People with low blood pressure may need their heads lower than those with higher blood pressure. Others may have some neck and shoulder discomfort from the new position. However, by experimenting with pillows under the arms, underneath the buttocks (which prevents sliding down the bed), and under the feet and legs, the patient should find a comfortable solution.
Also, when taking in to effect patient history, realize that neck injuries and tight neck muscles can impair venous drainage of the brain by compression of the jugular veins by the tight muscles. Neck massage and spinal adjustments may help improve overall brain circulation. We have had a few case histories where there was little or no improvement from head elevation, but the subjects had a history of neck injuries.
Of course, there will be times when people feel lightheaded and need to lie down to get more blood to the head. It might also be better for people to sleep less at night and to make up for lost sleep with a nap, or a siesta, during the day. That would avoid extremes of high and low brain pressure. But our culture makes it necessary for most people to do all their sleeping at once. Sleeping, after all, is a cultural issue. The point is to be aware of how you feel, and realize that your body position relative to gravity may be a key factor affecting health and disease.
We are continuing to research this effect of gravity and sleep position on health, and encourage practitioners to communicate their patients' experiences with us. We also highly encourage you to read our book, Get It Up! Revealing the Simple Surprising Lifestyle that Causes Migraines, Alzheimer's, Stroke, Glaucoma, Sleep Apnea, Impotence, and More! (ISCD Press, 2001), where we discuss the profound implications of this theory, including a lengthy list of references about brain pressure and various diseases and the effect of gravity on brain circulation. After you see the evidence, you will probably be as amazed as we are that sleep research has been ignoring this critical aspect of sleep.
Sleeping too flat each day may be the greatest lifestyle mistake people are making in our culture. Some of the worst diseases of our time may be all in our bed!
