01/02/2019 - Yawnder

What Is the Circadian Clock?

The word circadian is derived from the Latin term circa, which means “approximately,” and diēm, which means “day.” In humans and many other animals, this circadian rhythm is diurnal; this means that they feel active and energized during the day and feel sleepy after dark. Similarly, creatures like owls and bats are nocturnal; they sleep during the day and go out during the night.

The mechanism that controls these patterns is the biological clock. This is a 24-hour cycle influencing physical mental and behavioral changes in almost all organisms, from humans to microbes. It is the circadian rhythm that is responsible for determining sleep patterns, contributing to jet lag and is also behind morning grogginess during daylight savings. The National Institutes of Health has carried out a number of studies that show that the circadian rhythm also influences hunger, hormone production, body temperature, and cell regeneration. Conditions like obesity depression and seasonal affective disorder are also influenced by the circadian rhythm.

The circadian rhythm is responsible for so many things but what is responsible for the biological clock? The hypothalamus is what is responsible for controlling our biological clock. This clock is not made up of mechanical parts but groups of molecules that interact with one another in cells throughout the body. These molecules are governed by a master clock, situated in the hypothalamus. The group of nerves that control the biological clock from within the hypothalamus is called the suprachiasmatic nucleus (SCN).

Factors Affecting Circadian Rhythm

The biological clock or circadian rhythm is affected by a number of factors, both internal and external. The internal factors that affect the biological clock are the genetic makeup of the person and the proteins produced by the body. In a research by the University of California, a protein was found to be crucial in controlling the circadian clock in humans, mice, fruit flies, fungi and various other organisms. The other protein balancing it is in charge of sensing energy use in cells. Any disruption in the equilibrium of these two proteins can not only lead to insufficient sleep but also increase hunger. In the long term, this imbalance in the equilibrium can cause obesity.

The circadian rhythm is also influenced by environmental factors, such as light and dark. The SCN is situated right above the optic nerves, and they send information from the eyes to the brain. This means the location of the SCN is ideal for receiving information about incoming light. When the SCN senses less amount of incoming light, it asks the brain to produce more melatonin. This is the reason why we feel sleepy on cloudy and rainy days when the sun isn’t bright or during winter when the days are shorter and evening comes fast. This is the way that the SCN controls the sleep-wake cycles.

Circadian rhythm is best experienced during jet lag. When you travel from one time zone to another, adjusting your biological clock is not as easy as changing the time on your wristwatch. Jet lag usually involves “losing” or “gaining” time, and this disruption can make the body feel disoriented, particularly when the timings of light and day are out of sync. Even though the body eventually adjusts the circadian clock to the new environment, taking a return trip disrupts it again, and requires another reset.

When to Seek Help for Circadian Rhythm?

Occasional ups and downs in the circadian rhythm are normal and shouldn’t be a cause for concern. However, if you regularly experience disruptions in your circadian rhythm in the form of one or more of these problems, you should seek help:

Delayed sleep-wake cycle: If you fall asleep two or more hours after going to bed and wake up two or more hours after the usual waking time, you suffer from the delayed sleep-wake cycle. Although this is mostly seen in teenagers, it can affect anybody.

Advanced sleep-wake cycle: This is the opposite of the delayed sleep-wake cycle. In this condition, you fall asleep several hours before the normal bedtime and wake up several hours before the regular wake time.

Irregular sleep-wake pattern: If you have no fixed time for falling asleep or waking up, you suffer from an irregular sleep-wake pattern. People with this condition can sleep on and off at a stretch or in a series of hours. This usually indicates a severely disorganized circadian pattern.

Insomnia: If you’re regularly unable to fall asleep and spend most of your time awake in bed, you suffer from insomnia. Chronic insomnia can lead to sleep deprivation, resulting in various health problems.

Circadian rhythm is the mechanism behind our sleep-wake cycles. Sticking to a proper bedtime routine and maintaining sleep hygiene is the key to a proper biological clock.

Sleep is as common as breathing. We don’t need to wonder why it happens. It’s what we always do. Every living creature has a set time for sleep, including humans. It’s an intrinsic part of our daily routine, so normal that we never question our sleep habit.

The need for rest has existed since the beginning of time. Ancient humans had several other habits besides sleep that they later grew out of with the dawn of civilization. The eating habits have also changed as civilization has progressed. However, the need for sleep is something that has remained unchanged. The ancient man needed the same amount of rest that the modern man does. What has changed are the sleep habits and patterns.

While the need for sleep has remained unchanged, a lot has changed about the way people get their sleep. The ancient humans got their sleep in ways different than what we are familiar with today. Charles Darwin, the father of evolution, had first suggested the need for sleep by all living creatures. At first glance, sleep can seem like a bad idea. In fact, most people consider sleeping a waste of time. Being unconsciousness for several hours every day robs people of the time to accomplish various necessary activities. When creatures sleep in the wild, they also have the danger of being hunted down by predators. But sleep is something that everyone engages in, nevertheless.

Sleep is mostly needed because it’s a means to conserve energy and replenish the energy lost during the day. Energy is what helps us remain active and alert throughout the day, and without a period of rest, the body has no way to replenish the energy that’s being used up by the cells during the waking hours.

Changes in Sleep Patterns Over the Years

Most of us enjoy sprawling on a soft, comfortable bed in a quiet, cozy bedroom to go into snooze mode. But it wasn’t this way always. The sleep habits of humans have undergone significant changes over the centuries. Did you know that in the 16th and 17th centuries, people went to sleep as early as 6 in the evening? That’s because there was no electricity and nothing to do after dark. Turning out the lamps and going to sleep was also a way to save on energy because oil to light the lamps could be expensive.

After electricity was invented, people started going to bed later because they could work after dark. The dinner and supper times also changed, because people no longer had to go to bed because there was nothing to do. The invention of electrical and electronic devices such as the transistor and the television further influenced sleep patterns, because people enjoyed entertainment after work.

Over the years, sleep patterns, positions, timing, and bedding have undergone tremendous changes. Beginning from the early man to the Egyptians to the modern man, sleep has kept changing throughout the years.

Early Man: Very little is known of the early man’s sleeping habits. But from carvings on cave walls and other ancient documentation, it can be deciphered that they slept in beds of grass and other soft materials on the ground. Because these beds were small and round in shape, it is understood that the early men slept in the fetal position.

Ancient Civilization: At the beginning of civilization, the man had grown out of the wild stage, but still didn’t have the light of knowledge. Sleep, therefore, was a mystery, and people were scared of it. The Egyptians worshipped sleep because they considered it akin to death. With the dawn of civilization, the man had also started to make houses and beds to sleep in. For instance, the Romans had tiny bedrooms with low ceilings and small beds.

Middle Ages: In the Middle Ages, people had proper houses and rooms, but the whole family usually slept in one big bed, in order to conserve heat. Bedframes and mattresses had already been developed, while bedframes started to become ornate and decorative in China.

Industrial Revolution: This is the period when electric light sources are developed, and people start to shift from a mainly agrarian economy. Beginning from the Industrial Revolution, people start going to sleep later. They not only work after sundown but also enjoy reading and other forms of entertainment, thanks to electricity. Having separate bedrooms also becomes the norm from this time.

19th and 20th Centuries: This is the time when metal bedsprings are invented. During the latter part of the 19th century, the waterbed and the Murphy bed are invented. At the end of the 20th century, memory foam is invented and eventually becomes affordable enough for the average people.

21st Century: Sleep is a whole industry today, with various sleep aids and technologies to help people get sufficient and restful sleep. However, technology is also often the reason behind the lack of enough sleep.

Sleep Habits – Then Vs. Now

Sleep habits and practices, as well as bedding, have undergone massive change over the years. How we sleep today is dramatically different from the way our ancestors slept. From the duration of sleep to the types of beds, to the sleep patterns, everything has gone through various changes over the centuries.

During early civilization, beds were of no standard size. Beds were individually made, according to the size and preference of the person. However, today beds have standard sizes and aren’t usually made individually. Mattresses are usually customized, but bed frames are of standard sizes.

Sleep patterns have also changed over the years. Today, people have a monophasic sleep pattern, i.e., sleeping in one long chunk. However, earlier, people slept in two chunks of four hours each, with around two hours of break in between. During this break, people read, visited neighbors, or had sex. By the 1920s, this polyphasic sleep pattern had become unusual.

Bed springs were later used to support mattresses. But earlier, ropes and wool straps were used to make bedframes. Today, there are various types of bed frames, made from iron, wood, as well as engineered wood. Mattresses are also made of various materials and are often have computerized controls.

An interesting fact is that spouses slept in separate bedrooms, while all the children slept in one room. This is unlike today when spouses usually sleep in the same room while children have separate rooms.

Importance of Sleep

We tend to believe that sleep is a period of inactivity. But actually, sleep is when the body and the brain undergo various processes for rejuvenation, development, and growth. When we sleep, our body conserved energy and prepared for the next day.

Some of the things that sleep helps with are:

Learning
Memory
Mood
Appetite
Immune system
Heart health
Stress management
Weight management

Although science still cannot pinpoint exactly why we need sleep, we do know that it’s good for us. Going without enough sleep for a long time affects appetite, mood, productivity, concentration, weight, and physical health.

Benefits of Napping

When you’re sleep deprived, napping can provide much of the same benefits. Napping has been found to enhance productivity and performance, reduce accidents, and boost alertness. In some cultures, napping is a regular part of the daily routine. Workplaces have recently started making provisions for employees to nap during the day. Although napping can never make up for sleep, it helps to a great extent.

When napping, remember to set the alarm so that you wake up right after you complete one sleep cycle. Any longer, and you risk entering sleep inertia. Finding a quiet and dark place is also important. Napping is extremely beneficial to physical and mental health, so don’t feel guilty about sleeping in the middle of the day.