Unlocking the Secrets of Time: Chronobiology and Jet Lag​

Chronobiology & Evolution

An obvious question is why are circadian rhythms and chronobiology preserved in organisms throughout evolution and what are their crucial roles in survival. Circadian rhythms have been conserved across a wide range of organisms, from single-celled organisms to complex multicellular beings. This preservation strongly suggests the importance of these rhythms in promoting survival and adaptation to the environment.

The ability to anticipate and respond to environmental changes is essential for an organism’s survival.Circadian rhythms help organisms align their physiological processes with the predictable variations in their surroundings, such as the daily light-dark cycle. By synchronizing their internal biological clock with the external environment, organisms can optimize their behavior, physiology, and metabolism to match the varying demands of different times of day.

For example, in the animal kingdom, numerous species exhibit diurnal (active during the day) or nocturnal (active during the night) behaviors. These behavioral patterns are governed by circadian rhythms, enabling organisms to engage in activities such as foraging, hunting, or avoiding predators at the most opportune times. Maintaining these rhythms is crucial for successful adaptation and survival in their respective ecological niches.In addition to behavioral patterns, circadian rhythms also play a vital role in physiological processes. The regulation of hormone production, metabolism, and body temperature is tightly controlled by the circadian system. By coordinating these processes with the external environment, organisms can optimize energy utilization, nutrient absorption, and immune function.

The preservation of circadian rhythms throughout evolution underscores their fundamental importance.Disruptions to these rhythms, such as those caused by modern lifestyles with irregular sleep schedules or constant exposure to artificial light at night, can have detrimental effects on health. Such disruption scan lead to imbalances in hormone production, metabolic dysregulation, impaired cognitive function, and increased susceptibility to diseases.Understanding the evolutionary significance of circadian rhythms can guide us in making informed lifestyle choices. By aligning our behaviors and routines with our internal biological clocks, we can support our overall well-being and enhance our ability to adapt to the challenges of our modern world.Chronobiology sheds light on the preservation of circadian rhythms throughout evolution and their vital role in promoting survival and adaptation. By recognizing the importance of these rhythms, we can make conscious efforts to maintain healthy sleep patterns, synchronize our activities with natural light-dark cycles, and adopt lifestyle practices that respect our biological clocks. In doing so, we can optimize our physical and mental health, aligning ourselves with the biological rhythms that have guided life on Earth for countless generations.

The International Date Line

The international date line is centered around the Prime Meridian, located in Greenwich, England. ThisPrime Meridian acts as the reference point for establishing international time zones, with zero degrees longitude passing through it. These time zones are divided into 24-hour increments, starting from midnight GMT and ending at 11:59 GMT of the following day. The purpose of the international date line, positioned exactly 180° away from the Prime Meridian, is to organize time and date by creating a boundary that separates the world into different dates.

The establishment of international time zones took place in 1884 during the International Meridian Conference held in Washington, D.C. Representatives from 25 countries attended this conference and unanimously agreed to adopt Greenwich as the Prime Meridian and the universal standard for timekeeping. This decision was officially implemented in 1885 when universal time was adopted across the world’s railways.

Thanks to the international date line and international time zones, we now have a consistent and standardized method of timekeeping worldwide. This greatly facilitates international travel and communication, enabling us to stay connected with people from all corners of the globe. The international date line plays a crucial role in our global infrastructure, ensuring that everyone remains synchronized regardless of their location.

In addition, the establishment of international time zones and the international date line finally provided an answer to Pigafetta’s Paradox. As mentioned earlier, Antonio Pigafetta, a member of Magellan’s crew during their circumnavigation of the globe, had recorded in his diary that they had missed an entire day upon arriving in the Canary Islands. This paradox puzzled scholars for over three hundred years.However, with the establishment of the international date line, it became clear that as one travels across the line, the date changes. When crossing the line from east to west, one would skip a day, which explained Pigafetta’s experience. This realization resolved Pigafetta’s Paradox and provided a logical explanation for the anomaly he had encountered during his historic journey. The international date line’s role in dividing the world into two different dates helped bring clarity to this previously unanswered question in navigation and timekeeping.

A Summary of Jet Lag

Every year millions of people routinely fly on airplanes across multiple time zones. Most of theseinternational flights are in an east-west direction because so many of the international centers ofcommerce are in Europe, the United States, and Asia at similar latitudes. Because our bodies are used tofunctioning on a regular schedule based on our local time, it takes time for the body to adjust to the newarrival time zone and reset its internal clock. This can cause travelers to experience jet lag, a temporarysleep disorder that results from an imbalance in the body’s internal clock.

What is JetLag? The general symptoms include disruption of sleep, gastrointestinal disturbances, decrease vigilance and attention span, and a general sense of feeling malaise. Jet lag happens when people travel across multiple time zones and the time difference causes a disruption of their circadian rhythms. Although jet lag affects everyone differently, the common symptoms are fatigue, insomnia, headaches, dizziness, and irritability. The time difference can cause a disruption in sleep cycles as well as an overall feeling of fatigue, headaches, and difficulty concentrating.

The extent of the symptomatology depends on the number of time zones crossed; most people can cope with the crossing one single time zone, but virtually everyone would have a problem flying across 12zones. Traveling from the continental US to Europe exposes travelers to time differences that can range between 5-9 time zones, depending on the time of year and location. This wide time difference leads to significant disruptions in the normal time and structure of sleep and wake time because of disruption in circadian rhythms.

And generally, there is minimal consideration about the traveler’s health and little attention has been paid to the consequences of such changes on people with medical conditions.

It takes a significant amount of time for people to adapt to this change and troublesome impairment is the immediate consequence for many travelers.

Our story today begins with another cruise over 500 years ago from the port of Sevilla in Spain.

In 1519 the Portuguese explorer Ferdinand Magellan set sail from Sevilla under the flag of King Charles I of Spain with the plan to sail west across the Ocean Sea and find fortune in the Moluccas or Spice Islands in an area now known as Indonesia.

Sailing west to the Spice Islands had already been the dream of Christopher Columbus and others since 1492. After Columbus completed his first voyage and claimed the New World as possessions of the Spanish crown, a bitter disagreement arose between the two greatest seafaring nations at that time: Portugal and Spain. Columbus never acknowledged he had not reached the Indies and believed that China lay only a few hundred miles west of his landing in Central America. Portugal, already exploiting their route to the east established by da Gamma, asserted its claim to the discovered lands along with several other countries.

The Spanish crown, Queen Isabella and King Ferdinand, petitioned the pope, Pope Alexander VI to protect the discoveries of Columbus who had claimed the New World for Spain. Portugal, already exploiting their route to the east established by da Gamma, also asserted its claim along with several other countries.

A Spaniard by birth, Pope Alexander VI, named Rodrigo de Borja, was the nephew of Alfonso Borgia, who became Pope Callistus III. Later, Rodrigo also assumed the Italian surname Borgia before assuming the papacy. On June 7, 1494, Pope Alexander VI issued a papal bull and divided the world in half, bestowing the western side of the line to Spain without even mentioning Portugal in his decree. Only after twelve years and a new pope was the haggling completed and a new line further west was agreed to by Spain and Portugal.

By the time of Magellan’s voyage, it was still unknown how far Asia and the islands lay to the west. Perhaps if Magellan had realized how vast the distance was between the newly discovered land and the East, he would never have attempted such a dangerous trip.

Magellan began this journey with a flotilla of five ships (Trinidad, San Antonio, Victoria, Concepcion, and Santiago) and a crew of 240 men. Recruiting the crew was not easy because the pay was low and the danger high. The crew was a collection of men from numerous countries assembled from a mixture of Spaniards, Basques, Portuguese, Italians and others including one seaman, Master Andrew of Bristol, from England. Among the crew was a young Venetian named Antonio Pigafetta, who had signed on as a supernumerary. Pigafetta would become a great admirer of Magellan and the informal historian of the voyage. Over three years later only one ship, the Victoria, and eighteen men including Pigafetta and three slaves, returned. Half-starved, they were truly a skeletal crew. Magellan would not be one of them.On July 9, 1522, after 1125 days circumnavigation of the earth, the tattered remnants of the flotilla landed in the Canary Islands and re-established contact with Spain.