There is no more restorative agent than sleep. While one sleeps protein synthesis occurs. This is crucial because protein synthesis is the activity that lays the foundation for the proper functioning of all the cells in the body. During protein synthesis tissues are healed and physical and mental processes are restored. There is also an emotional healing component and perceptual learning occurs while one is asleep. Perceptual learning is the ability to discern the meaning of what we encounter through our senses of touch, taste, see, hear, or smell. If any of these processes are short-circuited, then the whole person suffers as the body is not able to heal or restore itself.
An Interesting Sleep Study…
In 1987, Thomas Wehr, a psychiatrist from the National Institute of Mental Health conducted a study using 15 men imitating the light exposure in the midst of the dead of winter in middle latitudes and its effect on sleep patterns. Various indicators were monitored throughout each night such as temperature, hormones, brain waves, etc. For comparison another set of measurements was taken later on when the men slept for only 7 to 8 hours as is more common today.
The results of the first study was amazing. “As the study volunteers adjusted to their artificial circumstances, their sleep patterns relaxed into distinct phases. The men slept only about an hour more than normal, but the slumber was spread over about a 12-hour period. They slept for about four to five hours early on, and another four to five hours or so toward morning, the two sleep bouts separated by several hours of quiet, distinctly nonanxious wakefulness in the middle of the night. The early evening sleep was primarily deep, slow-wave sleep and the morning episode consisted largely of REM, or rapid eye movement, sleep characterized by vivid dreams. The wakeful period, brain wave measurements indicated, resembled a state of meditation.”  The total hours equaling approximately nine hours per night. Up until as little as one hundred years ago our ancestors slept nearly nine hours per night, just as the men in this study with all the external stimulation minimized.
It’s Prolactin, More or Less
When people are sleeping with no artificial light at all they generally sleep twice every night. Called biphasic or bi-modal sleep, they go to bed around 8 p.m. and wake up around midnight, then sleep again from about 2 a.m. until daybreak. The hours in between first sleep and second sleep reveal a surge of prolactin that modern-day monophasic sleepers never experience.
In biphasic sleep between the first and second sleeps a higher level of prolactin is a secreted than when people sleep in one full “sleep” from evening until morning. As we know it, prolactin is that hormone produced by the pituitary gland that stimulates breast development and lactation in women. It is also necessary in males and non-lactating females at low levels to produce a feeling of sexual satisfaction. In birds, prolactin is the hormone that causes them to go broody and contentedly sit on their eggs for extended periods of time. It is this same hormone that also that produces the feeling of peace and contentedness in the wake phase between first and second sleep in biphasic sleep.
In Dr. Wehr’s study it was found that the men’s prolactin release was linked to the onset of darkness. During the long 14-hour nights, prolactin doubled shortly before sleep and remained high for the whole first sleep, wake, and then second sleep phases. However, once men returned to a modern eight-hour nightly sleep, the prolactin released stayed the same, but here is the clincher, it was restricted to that shortened time frame. Instead of 12 to 14 hours of increased prolactin each night, men are now getting at best eight hours, but likely much less.
This raises questions. One of them being, how does a minimum of six hours less prolactin release per night affect male physiology overall? Researchers know that men with prolactin deficiency often struggle with impotence and depression. WebMD states, “The research, published in the August 2003 issue of Annals of Internal Medicine, shows that ED is common among older men and sexual function sharply decreases after age 50.” Perhaps this is a hidden contributing factor to erectile dysfunction (ED) that ought to be explored.
It is interesting to note that the people in these studies feel so awake during the daytime that they say they have never experienced true wakefulness before in their lives.
Back in the Day…
Sleep prior to the 1600s included biphasic sleeping, a practice that most would be unfamiliar with today. This type of sleep described in literature as ‘first sleep’ and ‘second sleep was still a common occurrence with country folk or “laborers” as late as the 19th century. As the range of night, especially in the winter season could be as much as 12 hours in duration, people would commonly sleep for three or four hours and then wake for two or three hours, and later return to sleep until daybreak.
Those hours in the middle of the night were used for many reflective tasks such as prayer and meditation, reading, and studying, and sometimes other mundane tasks such as tending the fire, sewing, or chopping wood. Yet typically, this time was primarily one of reflection or socialization. If one was out and about and a neighbor had candlelight emanating from their dwelling that would signal someone was awake and ready for a bit of a social visit!
Illuminate the Night
In the preindustrial era until the industrial revolution, biphasic sleeping continued in rural areas while, towns and cities were having natural gas lanterns installed as street lights and even as a method of illuminating the interior of homes and industry.
This was readily accepted, especially by the wealthy, as lighting was useful to discourage theft as well as to provide opportunity for people to move about after dark.
In those early days of in-home lighting aristocrats continued to sleep in biphasic fashion, however, they began to go to sleep later, wake briefly, and then awake from second sleep much later, well into the morning.
A doctor from the 1500s explained the reason why the working class conceived more children than city dwellers was “that they typically had sex after their first sleep.”  While there is something to be said for romance, it makes sense that many women, especially busy mothers, might enjoy three or four hours of recuperative sleep before intimacy. The first phase of sleep is an extremely important restorative phase of sleep. We will discuss this in more detail later.
Historian A. Roger Ekirch found that “references to the first and second sleep started to disappear during the late 17th century. This is thought to have started in the upper classes in Northern Europe and filtered down to the rest of Western society over the next 200 years. Interestingly, the appearance of sleep maintenance insomnia in the literature in the late 19th century coincides with the period where accounts of split sleep start to disappear.” As people began to deny their natural biological rhythms to stay up into the evening, they became more fatigued upon awaking.
Although a number of early experimenters contributed to the invention of the incandescent light bulb, Joseph Swan and Thomas Edison developed a better design and Edison had the funds to commercialize the product. It was not long before he introduced the incandescent light bulb in New York City in 1882.
In May 1936, Congress passed the Rural Electrification Act as part of President Franklin D. Roosevelt’s “New Deal”. For the most part, this rural electrification was accomplished in the 1950s, yet even before that cities and towns were electrified. Street lights and urban homes already had the luxury of illuminating the night, causing the body’s biorhythms which had been embraced since the dawn of mankind to be ignored.
Work More, Sleep Less
World War II (1939-1945) called many women to the workforce. They were needed in these jobs to replace the men who had joined the military. Where before the war began most women fulfilled a culturally-accepted role of homemaker and child-raiser, now a full-time job beyond their full day’s work was not only encouraged, it became expected.
A famous cultural icon of this era was “Rosie the Riveter.” Rosie the Riveter stood for the many women who took factory jobs building aircraft, producing ammunition, and other supplies in support of the war effort. Long work hours added to family life also served to increase their daily stress.
Once having entered the workforce, many women continued to work after the war efforts ceased. The additional income helped the family to afford luxuries or “extras” that soon became necessities such as cars, store-bought food (because they no longer had the time nor the energy to garden.) Unfortunately, for the working mother, with the hours demanded by both job and family and the changing societal beliefs about sleep, the only place that could ‘give’ was her precious time for sleep.
Play More, Sleep Even Less
The 1950s saw the dawning of the age of technology. As the days continued to be filled with work and increased stress, people sought entertainment to help them relax. By the 1960s about 45 million homes had televisions across the United States and TV viewing grew to more than five hours per day. From there, video games, personal home computers, smart phones, and a host of electronic gadgets occupied free time and unfortunately time that might be better spent sleeping.
The following chart will help to visualize the stark reality of the changes occurring not only in the United States but in other countries as well. Life was getting increasingly difficult and stress had become an everyday word.
The year 1910 was used as a baseline as the amount of sleep that people got then was likely what was common throughout antiquity. 1942 is another marker when it was found that the average amount of sleep was reduced by an hour per night. By 1960, another hour was lost reducing the average amount of sleep each night by two hours from 1910! This translates into a loss of more than half-a-day of sleep each week. If this doesn’t blow your mind, at just seven hours of sleep per night, an entire month of sleep is lost each year!
A condition called “sleep debt” is created when the amount of sleep a person needs increases because they have not gotten enough in previous days. While people may think they can get away with having less sleep, this is not entirely true. What generally happens is that they become used to performing their daily routine in a deficit mode. The greater sleep debt that is incurred, the less the person is able to identify it.
Fortunately, the body is faithful to give warning signs when it does not receive enough sleep. Feelings of excessive sleepiness, yawning, irritability, and daytime fatigue drive people to consume caffeinated beverages to get through their day. These beverages are often counterproductive, making it even more difficult to fall asleep at night.
Microsleep, where one dozes off for a few seconds to a couple of minutes without noticing is another indication of being sleep-deprived. The EEG test results of sleep-deprived rats, reflect that certain parts of the brain fall asleep while others stay awake. Researchers to do not fully understand the mechanisms behind this.
Types of Sleep Deprivation
Full sleep debt is when a person is awake for a minimum of 24 hours. This is not as rare as it might seem. Think of any college campus when reports are due and exams are looming or a stressed working mother when her child is sick and she stays up all night and goes to work the next day, or computer programmers propping themselves up with coffee and energy drinks until an employer’s deadline is met.
Partial sleep deprivation is what most people experience at a more chronic level when sleep is not adequate for an extended period of time such as several days or weeks. One study found that “the results of those who slept for six hours each night for a period of 10 days were similar to those who are completely sleep deprived for one day.” It can be caused by not enough hours of sleep, disrupted sleep, or physical conditions like sleep apnea.
Sleep disruption can occur because of sickness, pain, or the use of pharmaceuticals such as alpha-blockers, beta blockers, corticosteriods, diuretics, SSRI antidepressants, medications containing alcohol/caffeine/nicotine, sedating antihistamines ACE inhibitors, ARBs, Cholinesterase inhibitors, H1 antagonists, glucosamine/chondroitin, and statins, Theophylline (an asthma med), and higher doses of thyroid hormone, as well as over-the-counter painkillers.
Alcohol has been shown to disturb the second half of sleep by increasing wakefulness after its initial effect of sedation, even when consumed up to six hours before bedtime. “However, alcohol consumed within an hour of bedtime appears to disrupt the second half of the sleep period. The subject may sleep fitfully during the second half of sleep, awakening from dreams and returning to sleep with difficulty. With continued consumption just before bedtime, alcohol’s sleep-inducing effect may decrease, while its disruptive effects continue or increase.”
Insomnia, or disrupted sleep is something that was almost never recorded in the history books two hundred years ago but has become commonplace in our modern culture. Insomnia includes having trouble falling asleep, staying asleep, or getting enough sleep. Acute insomnia is considered brief. It comes on with stressors such as getting bad news, anticipating a stressful event (good or bad) such as a test at school, financial stress, work stress, relationship stress, etc.
Among adults, “15 to 20 percent have a short-term insomnia disorder which lasts less than three months, 10 percent have a chronic insomnia disorder, which occurs at least three times per week for at least three months.”
The Four Stages of Sleep
Stage 1 – Lasts only about 5 – 10 minutes. Theta waves are produced by the brain as the body transitions from wakefulness to sleep.
Stage 2 – Lasts about 20 minutes. Body temperature begins to decrease and the heart slows down. Most sleep is spent in this stage.
Stage 3 – SWS (Slow Wave Sleep) – This is deep sleep where slow delta brain waves occur and the deepest sleep happens. During this stage muscles relax and blood pressure and breathing rate drops. This is also the stage where sleepwalking tends to occur. This relaxation helps to ensure the blood is circulating properly and that there are proper levels of blood glucose.
Stage 4 – Rapid Eye Movement (REM) or paradoxical sleep. “REM sleep is also referred to as paradoxical sleep because while the brain and other body systems become more active, muscles become more relaxed. Dreaming occurs due to increased brain activity, but voluntary muscles become immobilized.”
When sleep deprivation occurs, it is primarily of REM sleep and generally results in cognitive issues. REM sleep is believed to affect healthy moods, learning, and memory storage. During REM signals are sent from different areas of the brain to the body. Migraines may be triggered or increased due to increased expression of “the proteins p38, PKA, and P2X3, which are known to play an important role in initiating and sustaining chronic pain.”
“Researchers performed a study in order to determine the effect REM sleep deprivation has on the way a person responds to a stressful event. They applied mild electric shocks to participants while they slept and studied how their brains reacted. According to the results, the people who spent more time in REM sleep showed a lower level of brain activity related to fear than those who spent less time in deep sleep. The researchers believe that if a person is getting enough REM sleep, they might be less susceptible to suffering post-traumatic stress disorder (PTSD) after experiencing a fearful event.”
“It is important to realize that sleep does not progress through these stages in sequence. Sleep begins in stage 1 and progresses into stages 2, and 3. After stage 3 sleep, stage 2 sleep is repeated before entering REM sleep. Once REM sleep is over, the body usually returns to stage 2 sleep. Sleep cycles through these stages approximately four or five times throughout the night.”
While monophasic sleep is what most of us have known and practice, it is a relatively recent happening within the past two hundred years or so. Although there are many other factors that affect health we would be wise to consider the necessity of sleep in a culture that operates on the lack thereof. Sleep is the very thing the body needs to replenish and restore itself. Might it be presumptuous to entertain the thought that we have somehow “evolved” and no longer need those nine hours of nightly sleep that many of our ancestors received? That is likely.
Is biphasic sleeping preferable to a seven to nine hour monophasic sleep model? Perhaps. Then again, perhaps not. There is even a polyphasic sleep model for those whose interest is piqued, those who ‘wake up’ at the subject of sleep.
Each person is a unique individual who needs a certain amount of sleep to maintain good health. Chronic health conditions require even more sleep for the body to restore itself. Although it sounds good on paper, dis-‘ease’ can be caused by sleep deprivation because a solid seven hours may not be enough. The industrialized society is programmed to work around productivity-based paradigms and do not base their work upon the biological rhythms of the individual. While it may not be feasible to adapt to a biphasic sleep modality, even if that were the answer, there is much the individual can do to maximize the sleep structure to which they adhere.
Some may heave a great sigh of relief with the new understanding that waking briefly in the quiet of the night can be a normal part of the sleep cycle and not always an indicator of dreaded insomnia. Forearmed with knowledge, these peaceful moments can be enjoyed by leaving the bed for a brief time of prayer, meditation, or reading using dim, non-stimulating light, then to return to bed again as they begin to tire once more.
Are there lessons to be learned in looking backward to a simpler time when folks were more connected to their surroundings? In the comments below, share your observations whether biphasic sleeping might be a valuable health-promoting tool, or maybe not so much… We would love to hear your thoughts on the value of sleep.
In Part II of ‘Sleep Much?’ we will take a deeper look at the devastating effects of sleep debt on the psyche and physiology, discover techniques to make falling asleep easier, and discuss natural remedies and healthy habits for getting a much-needed restorative, enjoyable sleep!
11 REM Sleep: Why is it so important for food health by Dr. Amy Lee