Owls, larks and pigeons - human biorhythms

There exist Solar, Social and Biological time. Solar time is day and season rhythms of the Earth-light due to the planet rotation both around its axis and around the sun. Social time is the timing system accepted in the society. In strict accordance with social time people organize their work, educational institutions, public transport and so on. Biological time is the rhythm of the processes taking place in the body of all living beings.Biological time is studied by a special branch of the science – chronobiology. There are two main rhythms: circadian and seasonal.Human Circadian System has individual differences.The most expressed individuality in human circadian system are chronotypes. They are subdivided into 3 groups: early(«larks»), intermediate («pigeons») and late («owls»). «Owls» prevail among men, and as for children and elderly groups they are more likely to belong to «larks». «Owls» are found to be the most numerous group among adult people of the middle age [1; 3-5].

The aim of our research was to determine the chronotypes of students and professors of Medical Institute of Petrozavodsk State University. We interviewed 46 people: the 1st year students 17 people, the 2nd year student - 18 people, the professors - 11 people. In our investigation we used Horn–Ostberg test, which allows to determine the time of sleep and wakefulness which is psychologically comfortable for humans.

«Larks» belong to the early group. They rise at dawn and have the most productive activity until noon. Besides they go to bed at the same time and sleep the same number of hours every day. More than that, they come to the university ready to get new information. Sleep and wakefulness during the work week and week-end is just the same. But what is the most difficult for them it is to reorganize into another rhythm of life[1; 5-7], [2]. The number of «larks» among our respondents is illustrated on picture number 1 (pic. 1). Pic.1 The number of «larks»among our respondents

«Pigeons» arepeopleofdaylighttype. Their circadian rhythm is most adapted to the usual change of day and night. The period when they have the best mental and physical activity is from 10 to 18 o’clock. People with such chronotype combine active and passive temperament so many experts call them arrhythmics. «Pigeons» can easily adjust to any rhythm of life[ 1; 5-7], [2]. The number of «pigeons» among our respondents is illustrated on picture number 2 (pic. 2).

In «owls», unlike in other chronotypes, there is a lag behind the phase of sleep. They prefer to go to bed after 11–12 p.m. Most owls have three intellectual activity peaks. The first peak (day) takes place from 13.00 to 14.00 o’clock, the second (evening) — from 18.00 to 20.00 o’clock and the third (night) – from 23.00 to 01.00 o’clock. They are most active during the evening period. During the work week they don’t have enough sleep. It is hard for them to get information in the morning [1; 5-7], [2]. The number of «owls» among our respondents is illustrated on picture number 3 (pic. 3).

Pic.2 The number of «pigeons» among our respondents

Pic.3 The number of «owls»among our respondents
The middle of sleep phase during both work week and week-end varies considerably. Instability of rhythm phase sleep-wakefulness is a form of disorders, which is called «social jet lag». Figuratively speaking, it means that «owls» at the end of the work week «depart» across some time zones the number of which corresponds to the social jet-lag. The term «jet lag» is well known for people who often have long flights. For the first days after the flight a person gets tired quickly, experience deterioration of attention, decreased appetite and other symptoms. «Owls» have their «flying dreams» every week and they influence the well-being and even health [1; 6-7] [3; 144].

Numerous studies have shown thatstudents belonging to the late chronotype, study worse than their peers from intermediate and early chronotypes.It is important to emphasize thatthe level of intelligence in people with late chronotype is not lower, and even higher than in other chronotype.The reason of poor progress of «owls» is that they are not able to synchronize their biological clock with the social rhythms [1; 6-7].

According to our investigation in the 1st group (the 1st year medical students) 24% were «larks», 70% – «pigeons», 6% – «owls». In the 2n group (the 2n year medical students) a one third were «larks», 61% – «pigeons», 6% – «owls». In the 3rd group (professors of the Petrozavodsk State University Medical Institute) 18% were «larks», a halfwere «pigeons», and 27% «owls».

In conclusion, we want to stress that: according to statistics, in the world about 40% are «owls», 25% are «larks» and the rest are «pigeons», but according to the results obtained from Horne–Ostberg test, which we used in our investigation, approximately 20% of people are «larks» and «owls», the rest 60% are «pigeons».The modern style of life is mainly designed for the «larks», so «owls» have to adjust. It is necessary to reconsider the work of institutions, especially in the cities located near the western borders of time zones, bringing it into line with the physiological characteristics of the circadian system of man.

References
1. Борисенков М. Ф. Часовые пояса с точки зрения хронобиологии / М. Ф. Борисенков // Химия и жизнь, 2013 - № 1, С. 2-7
2. Индивидуальные хронобиологические хронотипы человека: «сова», «жаворонок», «голубь» [Электронный ресурс] // Все про сон. - Режим доступа: URL: http://vseproson.blogspot.ru/2012/05/blog-post_26.html; (Дата обращения: 25.03.2016)
3. Общая патологическая физиология / В. А. Фролов и др. - М.: ООО «Издательский Дом «Высшее Образование и Наука», 2009. - 568 с.
4. Черешнёв В. А. Патология: учебник: в 2т. / В.А. Черешнёв, В.В. Давыдова. - М.: ГЭОТАР-Медиа, 2009. - Т.1. - 608 с.

Abstract. The problem of biorhythms is an actual problem because rhythmic activity of the body as a whole, and its individual organs and systems, has the great importance not only for medicine but also for the social and economic processes. Thousands years ago, Chinese scientists and doctors have created the doctrine of the rhythm of the processes occurring in the human body, they believed that the knowledge of the chronotypes allows you to organize your everyday life, increasing work capacity and improving health. In the 1970-s the modern doctrine of chronotypes was born in Europe. Nowadays over 400 rhythmically varying processes of the human body is identified. In our research we consider circadian biorhythms which are congenital. Among them are such chronotypes as «Larks», «Pigeons» and «Owls» [3; 134-135].
Keywords: larks –жаворонки, pigeons –голуби, owls –совы, biorhythms –биоритмы, social jet- lag –социальныйджетлаг.

А. К. Куликова, И. В. Смусенок