Biological aspect - human clock - The Inner “Tick-Tock”
An interesting biological aspect which applies to the existence of all living things is the biological clock, even though the biological clock is not actually a physical part of an organism’s biology. For example: we all know that we would never find a clock built into our human anatomy—ticking away and keeping time inside of us even setting its own alarms! However, humans and other animals feel the effects of the biological clock every day. “An internal biological clock is fundamental to all living organisms, influencing hormones that play a role in sleep and wakefulness, metabolic rate, and body temperature” (“How Biological Clocks Work”). So, although humans may not always realize that they have biological clocks, they feel the effects of this essential biological mechanism every day.
The source of our biological clock is in our cell and neurological structures. This is another way of saying that our biological clock is partially controlled by our brains. In reality however, out biological clock runs on autopilot, with complete independence; we have no control over how it works. “The clock is a self-governing mechanism that is entrained to the day–night cycle by the hormone melatonin, released by the pineal gland in the brain during darkness” (“Animal Behavior”).
The twenty four hour cycle that our bodies work on is known as a circadian rhythm. “Circadian” is a Latin word which means, ‘about a day’. (“How Biological Clocks Work”). On Earth, our biological clock runs on a twenty-four hour cycle because a significant piece of it is triggered by simple daylight. Light from the sun passes through our eyes and is detected by nerves in the retina, which is a sensitive area at the back of the eye. These nerves pass a signal along to the brain. “Some of these nerves feed the hypothalamus, which is a part of the brain that regulates body temperature, water, sugar ratios, and also fluid secretions. It houses the suprachiasmatic nucleus, which is a bundle of nerves that controls the body’s circadian rhythms” (“Jet Lag”). This also explains why circadian rhythms affect body temperature. The temperature of our bodies rises during the day, drops in the middle of the night, and begins to rise again in the early morning (“Jet Lag”).
From an evolutionary point of view in the animal kingdom, we presume biological clocks were developed in part so that animals could be best prepared for various situations and opportunities, like an early bird taking off at dawn to get the worm (“Animal Behavior”). We do know for a fact that animals mate and migrate to a very definitive internal clock and timetable.
Although we, as humans, live on a twenty-four hour cycle, we must sometimes adjust to extreme situations and reset our biological clocks temporarily. Readjusting our biological clock can sometimes lead to problems. A change in jobs or lifestyle can often lead to drastic changes in our daily schedules which in turn affects our internal clocks and makes us moody or depressed. Adults who work the third shift—meaning that they are required to stay up through late hours of the night and early morning—are living backwards in terms of their circadian rhythm. The circadian rhythm would be saying that when it’s getting dark outside, it’s time to sleep and when it is becoming light outside, it’s time to wake up, which is totally opposite to the way you would be living.
The effects of serious illnesses can also be magnified in people who have readjusted their biological clocks. Sleep patterns can also be seriously disturbed (“How Biological Clocks Work”). One of the most common effects of a readjusting circadian rhythm is jet lag, which will be discussed further in another article. People should be mindful of the fact that they have a sensitive biological clock, and that its natural cycle should be disturbed as infrequently as possible.