[The author of this article is Jonathan, a guy in Colorado, who has a blog about Sleep. I tried emailing him but the address he posted wasn’t accepted by my email account, and he does not give his last name. I’m hoping he will see this and choose to write a comment about his discoveries. Meanwhile, I plan to read everything he’s written about sleep.]
Every night we as humans follow a curious ritual. As the daylight turns to darkness, a sensitive biological clock alerts the brain to send a chemical response throughout our body…
We change into comfortable clothing, perhaps open up a good book to read or watch a little TV to wind down the day. We recount the days’ events, as we make our way into our beds, cozy up under our sheets and comforters, and let our eyes slowly close…our minds wandering, imagining, thinking….drifting…
Our body becomes motionless, and our eyes roll from side to side. As the minutes fly by, eventually our eyes begin dancing and darting, rapidly moving as witnesses to mysterious and strange things called dreams. Our minds enter a highly active state — just as active as the waking hours actually — and we travel to strange and amazing places, exploring the deepest parts of our minds that aren’t normally as accessible to us during the day.
It’s almost as if our mind travels through some sort of portal, a wormhole to a strange dimension so to speak, curiously similar to our daily life as we know it, yet still very different. The funny thing is, when we’re dreaming, we don’t know we’re dreaming…
To us, in that moment, what we are experiencing is real…
Hours later, the sun rises and our brains excrete another chemical, and it’s as if we travel back through the portal, back into “reality,” our eyes open and we’re awake again…
The kicker is when we wake up we usually don’t remember a thing.
Table of Contents
- So What Just Exactly is Sleep?
- “Hypnos – God of Sleep”
- Circadian Rhythms and Zeitgebers
- Sleep Cycles
- Lack of Sleep Results in High Energy Consumption and Poor Performance
- The Ideal Amount of Sleep – How Much Is Enough?
- Too Much Sleep or Too Little Sleep: Which is Unhealthier?
- Which is better: too much sleep or too little sleep?
So What Just Exactly is Sleep?
It’s a complicated question as it turns out and sleep remains one of the unsolved mysteries of science. One theory is that sleep slows energy consumption so that the brain can perform other important functions. If this does not happen, the body begins to burn energy at an alarming rate, much like a vehicle that has been poorly maintained.
Utterly beguiling to humans for thousands of years, sleep is far more than the state of merely not being “awake.”
The state of sleep, and particularly dreams, have long played an important role for ancient people.
Many cultures believed that sleep is a “little death,” and that death is a “long” sleep. And some even go so far as to say that the soul leaves the body during the night and returns to the body when we wake up. Many cultures to this day consider the dream world to be every bit as real and important as the waking world. Other cultures believe that dreams provide guidance for daily life and that the dreamer has to act out the dream upon awakening to remain safe and healthy.
The ancient Greeks believed that Hypnos was the god of sleep, and Thanatos was the god of death, and the two gods were believed to be the twin offspring of the night. Often they were depicted as young babies, each one suckling on a breast of Mother Night.
“Hypnos – God of Sleep”
In the fifth century B.C. Alcmaeon hypothesized that sleep was caused by blood filling the brain vessels, and people woke when the blood left their brain. Plato and Aristotle believed that “vapors” from food decomposing in the stomach rose to the brain to cause sleep.
In fact, even in the 18th century, the most popular theory was that blood flowed to the head and put pressure on the brain, causing sleep, much like Alcmaeon believed over 2000 years earlier.
Thanks to sleep research and specialized machines, we now have a much clearer definition of sleep.
What we know is that sleep is essential for our health, and we know that the state of sleep is unique in that it creates a perceptual wall between the conscious mind and the outside world. Another defining feature of sleep is that it is immediately reversible. Even when someone is deeply asleep, intense and persistent stimulation will always awaken the sleeper. If not, the person is not asleep, but unconscious or dead.
Sleep occurs naturally and is also characterized by electrical changes in the brain, which scientists can measure using machines called electroencephalographs, or EEG’s. These machines can detect brain waves, and they measure and plot them much like how a polygraph is used as a lie detector.
Advances in science have moved us beyond the theories of the past, and we can now detect the inner workings of the sleeping brain. Scientists have discovered a pattern of brainwaves that are repeatable and predictable, and have divided them up into different stages of sleep.
There are 5 stages of sleep during the night, known as stage 1, stage 2, stage 3, and stage 4 sleep, and another distinct stage called REM (Rapid Eye Movement) which does not take place during any of the other stages.
Circadian Rhythms and Zeitgebers
Light, temperature, and other cues tell the brain when it is time to sleep. Manipulation of these factors can control circadian rhythms and create a good night’s sleep.
The vast majority of lifeforms on Earth are subject to the influence of daily biological rhythms, from sunflowers moving their massive heads to follow the sun across the sky, to laboratory fruit flies altering activity levels in response to temperature changes.
Humans are no exception to this general trend, and normally adapt to external time cues, known as zeitgebers, by altering their normal periodic fluctuations in hormones, brain wave patterns, and body temperature.
Biological clocks work on predictable schedules that follow natural patterns on a daily, monthly, or annual cycle. The Earth’s orbit around the sun, its rotation on its own axis, and the influences of moon cycles tell birds when to migrate, flowers when to bloom, and humans when to eat, sleep and reproduce. The fluctuations that occur on a daily basis, known as circadian rhythms, are largely governed by the influences of light and temperature fluctuations over the course of the day.
In today’s decidedly un-natural environment, the natural rhythms of sleeping and waking can be altered by 24-hour daylight and erratic work schedules. Working with the body’s natural reactions to external stimuli is a simple way to improve sleep quality and normalize circadian rhythms.
Circadian Rhythms in the Absence of Zeitgebers
According to Essential Psychopathology and its Treatment when humans are secluded in deep caves and isolated from external zeitgebers, their body clocks are forced to regulate based on internal neurological mechanisms. If an average person is placed in an environment devoid of zeitgebers, their biological clock increases from a 24-hour schedule to a 26-32 hour cycle.
This varies based on age as well as individual predisposition. Generally speaking, teenagers tend to have a much longer natural biological clock than adults. Because of this, they tend to perceive time as being earlier than it actually is. This explains, in part, why teens are so prone to staying up until all hours and sleeping late. Older adults, by contrast, have a shorter natural cycle that causes people to fall asleep earlier as they get older.
How Zeitgebers Influence the Body Clock
The shifts in day length with changing seasons naturally tell organisms when is the optimum time for biological activities such as sleeping and waking. It is not surprising, then, that according to the authors of Clocks and Rhythms (Stillman et al 2008,) the most powerful zeitgebers for most organisms are temperature and light.
Circadian rhythms are regulated by a number of neurological mechanisms and structures, chief among them the suprachiasmatic nucleus. According to Psychology (Santrock and Mitterer 2008) this small structure within the hypothalamus uses light cues obtained from the retina to regulate its own rhythm. It can then, in turn, influence other neural structures to stimulate biological activities such as sleep, wakefulness, hunger and body temperature in a way that works with environmental conditions.
In the modern world, other zeitgebers can override natural seasonal changes in day length. Some man-made influences on circadian rhythms include:
- artificial light
- externally regulated sleep patterns, such as shift work schedules
- clocks, radios, and televisions
- global travel
These factors can disrupt the body’s natural cycles, leading to disturbed sleep and delayed-onset sleep phase. In the absence of regular, predictable patterns of light and darkness, the structures of the brain may have difficulty reconciling the natural, internal rhythms with those of the outside world.
Using Zeitgebers to Regulate Sleep
For an average person, sleep cycles can often be regulated simply by carefully manipulating common zeitgebers. Falling asleep and waking up at the same time every day, and controlling the light and temperature of the sleeping area on a regular schedule will program the brain to release sleep-inducing hormones at the appropriate time.
By regulating the body clock, individuals can naturally stimulate sleep onset at a regular and predictable time. This is a natural, healthy, and drug-free way to ensure a good night’s sleep and an alert, well-rested morning.
Sleep research has identified, through the use of electroencephalogram (EEG,) five stages of sleep and two stages of wakefulness. These sleep stages represent progressively deeper sleep for stages one to four, with stage four being the deepest. The fifth stage, rapid eye movement (REM) sleep, is what is known as an active stage, and it is in this stage that dreaming occurs. Each stage of sleep or wakefulness is characterized by brain wave patterns recorded by the EEG.
Before the Sleep Cycle: Wakefulness
Wakefulness has two distinct phases, and most people can identify them without ever laying eyes on an EEG machine. Generally speaking, when people are awake, they are usually either active and alert, or relaxed and drowsy. For most people, these sleep cycles occur according to a fairly regular 24-hour biological clock.
Not surprisingly, there are correlating brain waves associated with each of these two states. When alert and concentrating, the brain exhibits waves on the EEG known as beta waves. Beta waves are typically the highest in frequency and the lowest in amplitude, and tend to not occur in any sort of consistent pattern, as the brain is usually responding to a multitude of sensory stimuli.
In a relaxed state, the brain waves slow down and become rhythmic. This is the state of mind experienced when almost-dozing in front of the television, or gazing absently out the window. Lower in frequency but higher in amplitude than beta waves, the brain waves associated with drowsiness are termed alpha waves.
Sleep Stage 1: The Onset of Theta Waves
As most will be aware, there is often a good degree of overlap between the states of restful drowsiness and early sleep. This overlap can be seen on the EEG as well. The shift from alpha waves to theta waves – the brain waves associated with early sleep – is a gradual one. Theta waves mark the moment where a “sensory curtain” drops and isolates the mind from the outside world.
At this stage, you no longer hear outside noises, smell outside smells, or feel the very mattress you’re sleeping on. Stage 1 is a light sleep, however a loud enough noise will still awaken you, and upon awakening, you would think that you weren’t even asleep at all. However, during this stage, you wouldn’t wake up if someone whispered your name because your brain is still fairly closed off to the outside world. At this stage, the eyes make slow back-and-forth movements. Stage one sleep is characteristically light, and generally lasts about five to ten minutes.
Sleep Stage 2: Theta Waves With Sleep Spindles
Stage 2 is a deeper sleep than stage 1, yet waking up from this stage would still be relatively easy. During these stages, the sleeping person is easily roused, and once awake, he or she might not be aware of having slept. Stage 2 sleep contain two sleep specific brainwaves called “sleep spindles” and “K-complexes,” which are very short bursts of wave activity lasting only two to three seconds.
So on an EEG machine, sleep spindles look like a “spindle” on an old spinning wheel, and K-complexes are large waves that appear to spike and come out of nowhere. These short bursts of activity represent with certainty that the individual is indeed asleep. This stage lasts for 5 to 10 minutes.
Sleep Stages 3 and 4: Delta Sleep
Stage 3 sleep is the first stage of “deep sleep.” At this stage the waves are deeper and more pronounced than the stage 2 brainwaves. Difficult to distinguish, stages three and four are marked by the onset of delta waves and are often referred to collectively as delta sleep. You can think of stage 2 waves as like small, boring waves at the beach — great for swimming but not much else, and stage 3 waves are like massive swells that come when there’s a storm — great for surfing. Sleep spindles and K-complexes are still present in stage 3.
This is the deepest phase of sleep, in which rousing the sleeping person is most difficult. Lowest in frequency and highest in amplitude, delta waves are least similar to waking brain activity.
When the sleep spindles and K-complexes are no longer detectable, the sleeper has entered the deepest stage of sleep, stage 4. This is also known as “slow-wave” sleep. At this stage it’s very difficult to wake up, the heart rate and breathing are regular and slow, and the muscles are completely relaxed. If roused during delta sleep, most people are disoriented and confused, and most likely to fall back into sleep. During this stage of deep sleep the body secretes growth hormone, which helps cells divide and multiply and build new tissue.
REM Sleep: The End of the Sleep Cycle
REM sleep, the fifth stage of sleep, is probably the most well-known stage of the sleep cycle. Once finished stage four sleep, the sleeping person gradually returns to near-wakefulness, however, instead of waking up or beginning again at stage one, he or she moves to active sleep.
In this phase you enter a somewhat lighter stage of sleep again and the sleep spindles and K-complexes of stage 3 reappear, which will last about 10 minutes or so, and then the eyes begin to jerk back and forth. Brain activity increases greatly at this point, and all voluntary muscles become paralyzed.
This period of sleep is called REM sleep and is the stage where we are dreaming. REM stands for “rapid eye movement.” The first period of REM sleep will usually last only about 10 minutes, and throughout the night move between deep and shallow sleep, alternating between REM and non-REM sleep, with the second half of the night being more dream-rich.
During REM sleep, brain wave patterns are similar to those seen in relaxed wakefulness. REM sleep includes most of the dreaming that takes place during the night, and is thought to play a role in memory and in the brain development of children. Babies and young children spend significantly more of their sleeping hours in REM sleep than adults.
The Sleep Cycle During the Night
Every 90 to 100 minutes during the night, the brain completes one sleep cycle. During the first half of the night, the largest portion of the sleep cycle is spent in deep sleep. As the night progresses, an increasing proportion of sleep is spent in the REM stage. As a result, it is during the second half of the night that the majority of dreaming takes place. Over the course of a typical night in a healthy adult, about 60% of sleep is spent in light sleep, 20% is spent in deep sleep, and another 20% is devoted to REM sleep.
Lack of Sleep Results in High Energy Consumption and Poor Performance
According to a study of energy consumption during sleep, the body sleeps to save energy for renewing and maintaining critical biological processes. When we are sleep deprived, we begin to expend large amounts of energy just to keep functioning.
The authors of the study explain that the body sleeps to conserve energy. When we bypass opportunities for quality sleep, we burn excess energy just to perform at minimal capacity.
The study by Christopher Jung and Emily Frydendall, entitled “Energy expenditure during sleep, sleep deprivation and sleep following sleep deprivation in adult humans,” (2010) focused on the cost of sleep deprivation in terms of energy expended by the body.
We know that the body expends less energy during sleep than during our daily activities. Jung and Frydendall also discovered:
- Sleep conserves more energy than previously thought.
- Sleep deprivation results in energy consumption at a much faster rate than normal.
Their research showed that one night without sleep costs the body the same amount of energy as a two-mile walk. Even though subjects were confined to bed rest during this tightly controlled study, their energy consumption rose 7% after 40 hours without sleep (24 hours of sleep deprivation).
Why the Body Sleeps to Conserves Energy
Jung and Frydendall believe that the body needs to enter into a state of energy conservation in order to harness the fuel needed to support other critical processes, such as replenishing immune system function, production of hormones and reinforcement of neurological pathways that enhance memory and learning.
The reasoning behind this is well documented. Sleep deprivation commonly demonstrates significant impairment in mental, emotional and cognitive health.
Purposeful Sleep Deprivation Not Recommended for Weight Loss
The researchers emphasized that sleep deprivation should never be used as a means of weight loss in the hopes of increased energy consumption. Facts from numerous studies show clearly that chronic sleep deprivation contributes to obesity.
Sleep deprivation significantly reduces stores of the hormone leptin, which signals feelings of satiety when we eat. Many studies show that sleep deprivation is associated with present and future weight gain.
Mystery of Why We Sleep: The Body Conserves Energy
If the body does not sleep, it must expend extra energy just to maintain minimal function. In simpler terms, we sleep because our body needs to rest. Sleep disorders are serious health problems. This study provides another path of research for understanding and treatment of sleep disorders.
The Ideal Amount of Sleep – How Much Is Enough?
Although individual sleep needs will vary depending upon age, health-related issues, and individual genetic differences, certain generalizations seem to apply. Studies have shown that sleeping less than six hours a night not only increases the risk of specific health problems such as obesity, diabetes, and heart disease; it also increases overall mortality.
On the other hand, sleeping too much may have its downsides too. The Nurses Health Study showed that not only did short sleep durations increase the risk of heart disease, but sleeping longer than nine hours a night also increased the risk of coronary artery disease, the most common form of heart disease.
Based on the results of these and other studies, most experts believe that between seven and nine hours of sleep per night is the ideal amount of sleep for most people. As a generalization, younger people need more sleep than older people. Teenagers may require a full nine hours, while seniors usually feel their best at around seven hours or even less.
Although some people, usually older adults, report feeling their best when they get only five or six hours of sleep each night, there may be unforeseen health effects if the current studies hold true.
Too Much Sleep or Too Little Sleep: Which is Unhealthier?
Both too much and too little sleep can have negative effects on your health.
Everybody sleeps. While scientists don’t exactly know the reasons for sleep, it’s agreed that sleep is a period of rest for neurons in the brain that are active all day. It’s a time for our body to basically just let go and rest. We’ve all heard that eight hours is the optimal time for most adults.
Too much sleep?
Hypersomniacs experience excessive daytime sleepiness or nighttime sleep that lasts longer than normal. Sleepiness occurs repeatedly in the middle of the day and is not relieved by resting or naps. Patients often feel disoriented when they awake from sleep and it can also take them longer to transition from a sleep state to an awake state. But not everyone who oversleeps is diagnosed with hypersomnia.
Oversleeping has been linked with a whole host of things: diabetes, heart disease, and an increased risk of death.
Too little sleep?
One of the most common medical complaints, insomnia is a difficulty in going to sleep or remaining asleep all night. Because the body does not get enough sleep, the person may feel tired and sluggish throughout the day. Missing sleep also creates in your body a “sleep debt,” where those hours have to be made up at some point to feel normal again.
Too little sleep can cause memory problems, depression, a weakening of the immune system, and an increased perception of pain. The less sleep you receive, the apter you are to make rash decisions and to be cranky.
What about no sleep at all?
In 1964, Randy Gardner of San Diego, California, decided to experiment and see how long he could go without sleeping and report it in his local science fair. Using no drugs, not even caffeine, Randy had friends who would monitor him, help make sure he wouldn’t doze off and assist in redirecting his focus to something other than sleep. He spent a great deal of this time playing basketball at the behest of his friends.
The time he stayed awake ended up being 11 days (264 hours), which beat the time of the previous record-holder, Tom Rounds of Honolulu, HI. At the end of the 11 days, Randy gave a press conference in which he spoke clearly and there were no signs of slurring or stumbling his words, appearing to be in excellent health.
In the early 1980s, experiments were performed on rats by a researcher at the University of Chicago. After 32 days of total sleep deprivation, the rats had all died. None of the researchers agree on exactly what the cause of death was. They state hypothermia, the lessening of the immune systems causing illness, brain damage or even just extreme amounts of stress.
Scientists have extrapolated this to mean that if humans were to do the same, there would be a good chance of morality with us as well.
Which is better: too much sleep or too little sleep?
A study, published in the Archives of General Psychiatry published in February 2002 based on interviews performed by the American Cancer Society in 1982, asked participants about their sleep habits, how long they typically slept as well as their frequency of insomnia. Over 1.1 million men and women participated in this study, their ages ranging from 30 years to 102 years.
The results of the study noted the best survival rate was found in people who slept, on average, about seven hours a night. On either side of this line, both participants who slept in excess of eight hours a night and participants who slept less than six hours experienced a marked increase in mortality hazard. This higher risk increased by 15% for participants who slept more than 8.5 hours a night or less than 3.5 or 4.5 hours.
According to the research studies above, I believe that it is better to try and keep your sleep schedules as regular and as normal as possible. If you sleep more than 10 hours a night and are still sleepy throughout the day, you may want to see your general care practitioner to determine if there’s something that you need to do.
We all experience insomnia from time to time; however, if it gets to the point where you are simply not sleeping, again, I would advise that you call your general practitioner. Only they will be able to talk to you and assist you with your specific case.
If you liked this article, please got to https://www.betternightsleep.org/what-is-sleep/ to read his other research-based articles about sleep.
Till next time,
Please be kind to everyone you meet for we all have our hidden sorrows. ~Tzaddi