It was a nightmare. I had to have a flight for 16 hours to get here from Korea. That was two month ago, and there was a new stage of nightmare. I suffered a lot from the flight. After arriving here, I cannot sleep at night but in daytime I cannot resist to desire to fell into sleep literally everywhere even at a mall. The peak time was from 12pm to 2pm. That was 2am to 4am in Korea when I used to go to bed. Meal time was also totally different from here. It seemed like my biological clock was following Korean time. It took almost a week to get used to the new time zone.
This is a quite interesting subject, the circadian clock. There is a clock in our body, also too animals and plants, what makes us sleep and eat regularly. This is called the circadian clock, the biological clock, the biological cycle and so on. Because this moves in a cycle, usually 24 hours, like a clock goes. This clock regulates our eating, sleeping time, and hormones according to our body's time table. If the circular system breaks down, there would be lots of troubles starting from sleep deviation, gaining weight or losing weight. It has a great influence on our lives. Therefore, it comes as no surprise that many people including me have a great interest in it. However what I am particularly interested in is how the biological clock is set up following 24 hours.
Even though still there is somewhat controversy, this is largely accepted that the exposure to light affects our biological rhythm. To be exactly, there is an event in the level of cells and protein for the bio-clock. This article contains information about it detailed mentioning a scientific experiment of Amita Sehgal and colleagues. Actually this article conveys the experiment in an appropriate way. This explains the hypothesis, experimental procedures, and the conclusion. According to this article, there is a kind of protein named 'timeless' which plays an important role in bio-clock. At first, affected by sunlight, cells are broken down into timeless protein. Then the level of timeless affects out bio-rhythm. Actually there are lots of studies based on the molecular level for decades.
Moreover there are many issues and controversies over the circadian clock. To be specific some scientists believe that temperature regulates the bio-clock and there are some studies about it. This link has one of them. There would be more controversies over the issue so that it will be more interesting and fascinating.