The Nobel Prize in Physiology or Medicine for 2017 was released on October 2. The recipients of this prestigious award were three Americans. Jeffrey C. Hall, Michael Rosbash and Michael W. Young received the prize jointly “for their discoveries of molecular mechanisms controlling circadian rhythm,” according to a press release from the Nobel Assembly.

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Alfred Nobel established the Nobel Prize in his last will and testament in 1895. Prizes in various subjects, including physics, chemistry, medicine, literature and peace, have been awarded almost every year since 1901. In 1969, the Nobel Prize for Economic Sciences was added, according to the official Nobel Prize website. The winners first have to be nominated, and then a committee chooses from the list of nominees.

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Circadian rhythm, the internal, biological clock that regulates a regular rhythm of the day, has been a subject of research for many years. Past researchers have looked at whether the sun is the controller of circadian rhythm, how it is controlled in the brain, what happens when circadian rhythm is disrupted, and more.

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Fruit flies were used as a model organism in this research. A model organism is a species that has been widely used in research and is usually easy to maintain and breed in laboratory settings. These species, such as E. coli and zebrafish, are well understood since a large amount of data have been compiled about them.

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To study the circadian rhythm, the researchers isolated a gene that controls normal daily biological rhythm. This gene encodes a protein that accumulates in the cell during the night and is degraded during the day. They also found additional protein components of this process and exposed the mechanism that is responsible for the self-sustaining clockwork inside of the cell. The same process happens in other multicellular organisms, including humans.

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This research began in the 1970’s when Seymour Benzer, an American physicist, biologist, and behavioral geneticist, and his student, Ronald Konopka, found an unknown gene that disrupted the circadian rhythm in fruit flies. They called this gene “period.” This year’s Nobel Laureates wanted to discover that the rhythm worked and find the gene. The three were successful in isolating the period gene, and Hall and Rosbash were able to discover the protein that encoded period accumulated at night and degraded during the day. They also found that the protein levels follow a 24-hour cycle.

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This also showed that there are physiological changes when the internal rhythm and external environment do not match up, like jet lag. There are also signs that a chronic difference between the internal rhythm and the external environment can increase risk  for various diseases.

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The Nobel Laureates will be awarded their prize on October 10 in Stockholm, Sweden, and will meet with the Swedish royal family as part of the 111-year tradition.