What changes are the living things' sleep cycles in the bright 24 hours' white night '?
By Judith
It is known that creatures of the earth including human beings are equipped with a mechanism called "body clock" or biological clock . It is thought that the cycle of the biological clock is decided mainly by the morning sunlight that the sun rises, but the "white night" seen in the Arctic and Antarctic zones makes such a rhythm go wrong. However, creatures living in the Arctic Circle are thought to acquire the ability to respond to such unique situations in the process of evolution.
How Does the Summer Solstice Affect Animals?
https://www.livescience.com/62870-summer-solstice-animals.html
The summer solstice where the daytime is the longest in a year will come around June 21 every year. This phenomenon occurs due to the inclination of the Earth's axis, and summer solstice is thought to be the most important day in people's life from the old since along with the winter solstice.
What is summer solstice? - GIGAZINE
It is considered to be "brightness" brought by the morning sunrise every morning to human rhythm of the body clock. This is called a circadian rhythm, and the rhythm is adjusted by the change of light and dark in the day caused by sunlight as a stimulus.
It is often said that "the sunrise light resets the body clock" is the function of the circadian rhythm, but in the summer it will be like the area close to the Arctic Circle, the sun will be on the horizon for 24 hours In the area where the white night that continues to exist in this area, this circadian rhythm may deviate. For many human beings living on the earth, "sleeping if it gets dark at night, waking up when it gets bright in the morning" can be said to be a typical pattern of sleeping and getting up, but in the bright white night area, that cycle is created This is because the rhythm of light and darkness is completely lost.
In areas where such sun does not sink at all, there are times when events are sometimes held that says "the sun will not set". One such example is an all-night golf tournament "Midnight Sun Golf Tournament" held in Dawson City, a city in the Yukon Territory of Canada. The 2018 fiscal year will be held on June 23.
Midnight Sun Golf Tournament - DawsonCity.ca
https://dawsoncity.ca/event/midnight-sun-golf-tournament/
One of the reasons that humans can hold such an event is that the biological clock is susceptible to the surroundings, that is, "the biological clock is apt to go wrong". In the research contents announced in 1974, it has been shown that it is very difficult for humans to keep a sense of time without using watches in the bright or dark environment.
However, some animals living in the area where white water is coming have been adapted to such a special environment. According to Associate Professor Collie Williams, a biologist at the University of Alaska Fairbanks, a bird of about 15 cm in length is a kind of such a creature, with the feature that sleeping time is not affected by changes in night length It is. According to Mr. Williams, Hiraishi Tonen's pair (couple) has created a situation where two animals repeat sleeping and getting up alternately, always keeping ongoing either situation, the cycle is "in 24 hour period It is not a thing to move by casting. "
By Mick Thompson
A reindeer with a big horn on his head is also a kind of creature that is not affected by white night. Reindeers do not sleep in the night when they gather up, but have a cycle of taking a short sleep at the timing of digesting them after eating food. There is no circadian rhythm like human beings there.
According to Williams, such features are only found in living creatures that live in polar regions. In areas where the time difference between day and night is large, the benefit of working in a specific time zone is lost. For example, even if you have a nocturnal lifestyle pattern that saves energy or protects you from the natural enemy at night, the merit is that it does not make any sense at the summer time when the night does not come. It is because it becomes it.
In this way, the creatures in polar regions have a different life pattern from those in other regions, but on the other hand it is also true that there are living creatures with patterns of life based on circadian rhythms Thing. According to Williams, the polar bean, Lycheolus, is sticking to the pattern of behavior to return to the nest in order to save energy when it is in the evening even in the summer even in summer. Meanwhile, the polar beil spirits hibernate during the period from September to April. Therefore, it is likely that polar bean is a living creature with both a life pattern based on circadian rhythm and a life pattern based on season.
Scientists engaged in research in the same field as Mr. Williams are still continuing their studies on the differences between animals that hold circadian rhythms and those that do not. Meanwhile, scientists are impressed by how the creatures change their living patterns against the Earth's environment, where the average temperature continues to rise for about a century.
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