Circadian Clocks and Biorhythms

We have all heard the expression - 'my biological clock is ticking', and that is truer than most people think. Within our bodies we have a clock that tracks our timetable daily, and has a core effect on our sleeping habits, and other activities. Travelling for pleasure or work can be adventurous; however roaming into different time zones can deliver jet lag. The drowsy feeling you experience after the flight is due to the disruption in your natural circadian rhythms. These conditions happen when your biorhythms adjust sluggishly to the new time zone, lingering in the previous biological timetable for a few days. Your internal clock is experiencing a different time within your body compared to real time, so your body could be telling you it is time to take a nap when it is actually mid-afternoon, or keeping you awake when it is long past bedtime. All living creatures have an internal clock, known as the circadian clock or rhythm, which assists their physical body within the daily life cycle. The 24 hour rotation of the Earth determines night and day, and the term circadian originates from the Latin circa Diem, which means about a day. Occurrences, such as jet lag, initiate a conflict in the usual sleep patterns that are natural to our bodies. Due to the change in time and light cycles on the brain, the circadian clock modifies the regular sleeping patterns inflicted on the body, bringing it into the adjusted patterns. Therefore, jet lag has the tendency to leave travellers with a tired feeling, depriving them of the ability to function as sharp as they would if their rhythms were not disturbed. The limitation of these symptoms is not just limited to travelling to new time zones; it can happen in every day life.


When you force your body to keep extended and unbalanced hours, without sleep, you are disrupting your biological clock. It is imperative to have a set sleep routine, permitting you to have sufficient quality sleep.

Working shifts

Once you understand how your internal timekeeper operates, it is simple to perceive what effect an irregular schedule has on it. Working in different shifts fashions a misalignment between the external world and your internal clock. Since this creates confusion in the circadian clock, your body is sending you signals that are contradictory to the actions you want to perform. When you are working the night shift, your body discharges chemicals that cause you to feel drowsy, or prompt you to be awake when you need to sleep. As with any clock, our biological clock can adjust, as it is flexible. If you require the modification in alertness, it is imperative that you expose your body to light according to the schedule of the new time zone. Unfortunately, when you are working shifts continuously, it is like having jet lag all the time, as your circadian clock does not get the chance to adjust completely, or even to catch up. Even with a non-rotating shift schedule, you may need to sleep during the daytime hours, which can be challenging. It may well happen that you fall asleep swiftly after a night shift. However, it is probable that you will have trouble sleeping your required seven to eight hours continuously as your body sends you signals to be awake. The opposite is also true for staying awake at night when your body urges you to sleep.

What control our circadian clocks?

Proteins determine our circadian rhythms, rising and falling in rhythmic patterns. These fluctuating biochemicals regulate several functions within our bodies such as when we sleep, rest, wake up, and when we are active. Additionally it controls our heart activity, blood pressure, body temperature, hormone secretion, oxygen consumption, and metabolism. However, the functions are not limited to just these, as they also control the level of elements in our blood. These include blood sugar, ions, red blood cells, and oxygen. Even more so it can affect our moods; wintertime depression is an example, identified as SAD or seasonal affective disorder. A circadian clock consist of three parts: the means to receive response from the environment such as temperature or light, the chemicals and proteins to run the clock itself and then the elements assisting it to control alternative activities of the genes. Scientists discovered the controlling genes; period (per), cycle (cyc), clock (clk), timeless (tim), and others in the past few decades, in humans, insects, plants, and even single-celled cyanobacteria.

Where do we find the body's master clock?

The suprachiasmatic nuclei (SCN), located in the hypothalamus of the brain, hosts the circadian clock. SCN consists of two miniscule clusters containing thousands of nerve cells able to tell time, through external impulses including light and dark. The SCN controls metabolism, hormone production, and sleep. The belief is that the SCN can monitor and synchronize the confined clocks hosted in the organs and tissues of the body, utilizing hormones or alterations in the body temperature. Though the core pacemaker's location is in the brain, studies found gene operated clocks functioning independently in the testis, lungs, muscle, and connective tissues. Fruit flies deliver an example of a local clock, situated in their antennae. These cells demonstrate circadian rhythm independent from the master SCN located in the brain. The antennae fluctuations relate to the sense of smell, being more responsive during the night as during the day.

Do our circadian clocks correspond with the 24 hour clock we are accustomed too?

The answer to this question is not precisely. The circadian clock is, in fact, ten to twenty minutes longer than a typical 24 hour day. Academics found that it varies between species, and the rhythms could range from twenty two to twenty eight hours. No daylight is required for your SCN to continue in its natural cycle. However, as soon as the eye receives daylight, the biological clock resets to adjust to the Earth's 24 hour day. According to a computerized simulation, the conclusion reached was that the competition amongst certain species regarding food, as well as other resources, is fierce within both the day and night. It is less probable to share resources when not consuming them at the same time. Therefore, some species have diverse biological clocks, aiding them to endure the competition. Motivations for migrations, hibernations, as well as changes in the firs of numerous animals, happen through the stimulation received by their circadian rhythms. As the animal brain processes the changes in the environment, it activates a hormone excretion influencing the events.

How do the clock genes function?

There are no cogs and wheels in our biological clocks; instead, it is groups of interacting molecules, found in the cells in our body. The primary function of the SCN is to synchronize everything. Genes and the proteins they produce is what causes our clocks to tick. A severe disruption in your gene or protein balances can cause obesity. The genes are groups of instructions that program the clock proteins, interacting during the day to manufacture the variation levels in protein. The 'per' gene is the principal player, coding the 'PER' protein to increase its levels during the early evening and decreasing its level early morning. Viewing the cycle in a fruit fly, the 'clk' and 'cyc' genes work as a team to activate the 'per' and 'tim' genes to produce protein. The 'PER' and 'TIM' proteins combine and collect in the cell center, slowing down the 'clk' and 'cyc' genes. The 'cyc' deactivates the 'per' and 'tim' genes, making the production of 'TIM' and 'PER' proteins stop. With the reduction in the 'TIM' and 'PER' proteins, the 'cyc' and 'clk' genes commence a new cycle.

In 2001, scientists studied FASPS, a sleeping disorder that causes you to sleep early and wake up long before daybreak spontaneously. CLK or clock genes keep us awake throughout the day and let us sleep effortlessly at night. They found that the 'per' gene underwent an alteration, causing modifications in the sleep patterns.

Health implications

Now that we understand how the clock genes function, scientists may have the ability to create medications that can adjust the human circadian rhythms in cases such as jet lag, winter depression, and night shifts. Academics are now capable of discovering probable resolutions for sleeping disorders, increasing the effectiveness of medications consumed at certain times of the day. We now know that our biological clocks are built in timekeepers, and disrupting them can have an intense influence on your mental as well as physical health. Studies done on mice, in a 20 hour day/night cycle for ten weeks, to evaluate the influence on their metabolism, behaviour, and mental acuity, reflected astonishing changes. These mice grew fatter, had a decrease in mental flexibility, and were impulsive compared to mice in a natural habitat. As the circadian clock drives the biological rhythms on the cellular level, the effects go all the way through your body, explaining why sleep deficiency influences health.

Your circadian clock regulates your daily cycle of alertness by altering diverse parts of your brain with the assistance of neurotransmitters. To improve your short term memory, the section of your brain known as the hippocampus must be excited, to allow the structuring of your day in such a manner that will enable you to recall it later. Without proper functioning of the timekeeper, the brain release excess GABA, which can lead to short term memory difficulties, barring you from remembering and retaining new information. Adequate sleep improves performance, memory, and absorbing abilities, by enhancing your creative capability to unravel unique connections amid seemingly unconnected ideas. Sleep shortages have an influence on your metabolic hormone levels, which regulate hunger and satiety. If you suffer from diabetes type 2, too little and too much sleep can cause a significant increase in diabetic risk. The recommended amount is six to eight hours. A similar relation occurs between sleep patterns and coronary heart disease.

When you've had sufficient sleep and are revitalized, it is likely that you have a stronger immune system, providing your body greater protection against virus infections. The belief is that the discharge of certain hormones occurs during sleep, improving your immune system. The hormone melatonin subdues tumour development, and the release of this hormone transpires while sleeping. This hormone has antioxidant qualities that assist in reducing damaging free radicals in the body, and pacifies the production of estrogen, a cancer activator. When your sleep patterns and rhythms are disturbed, it could lead to a reduced production of melatonin, reducing your body's capacity to fight cancer.

According to reports in The Journal of American Medical Association, insufficient sleep can aggravate further serious and chronic diseases; including parkinson disease, multiple sclerosis, behavioral problems in children, alzheimer disease, and kidney disease, among others. Bad sleeping habits correspondingly tend to increase your corticosterone levels, the stress hormone connected with road rage. When your body experience stress, it discharges hormones responsible for the rise in your heart rate as well as your blood pressure. Your digestive system stops, your muscles tense, and it triggers some brain centers by modifying your brain chemistry. If you leave this unchecked, the response to stress can cause numerous health issues such as indigestion, headaches, anxiety, depression, and high blood pressure. The consequences of engrossing in a 24/7 routine runs the scope from insignificant stresses to severe health complications.

Create a regular rhythm through your light exposure

Consistent and regular exposure to light throughout the day, and sleeping in complete darkness, contribute to your natural circadian rhythms. This routine improves your natural melatonin production levels. A typical scenario today in the workplace is incandescent and fluorescent light, which release poor light quality, insufficient for your body to function at an optimal level. Your body requires full spectrum light, which is only obtainable outdoors. The opposite is true for the nightfall when you want a reduced exposure to the amount of light you receive. Low blue light bulbs are ideal for this purpose, emitting a light amber contrary to the blue, which reduce the melatonin productions. It is perfect to use in your living room, bathroom, and bedrooms. Computers and TV's also emit blue light, stealing your melatonin when utilizing them after dark.

When it is bedtime time make sure your bedroom is pitch dark with no light entering the sleeping area, as the smallest amount of light can suppress the melatonin production. How much do you need to sleep? The correct amount depends on you as the individual; there is no perfect number of hours. However, studies reflect that sleeping for less than eight hours a night continuously has substantial snowballing results. Listen to your body, and adjust as your body requires.

As a conclusion, it is crucial to understanding that though you may be doing everything right in your diet, your exercise plan, and managing your stress levels., without proper sleep, your health is destined to suffer in several ways. Take your sleep seriously, and align your lifestyle closely to your circadian rhythms.


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