Geographia Polonica (2013) vol. 86, iss. 1

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Lighting characteristics during the polar day and their impact on changes in melatonin secretion

Joanna Wieczorek, Krzysztof Błażejczyk, Takeshi Morita

Geographia Polonica (2013) vol. 86, iss. 1, pp. 67-75
doi: https://doi.org/10.7163/GPol.2013.8

Abstract

People traveling between climate zones can be exposed to extreme environmental stimuli which significantly differ fromtheir place of habitual residence. A move from the temperate climate of Central Europe to the subpolar climate ofnorthern Europe means exposure to great changes in two climate parameters: lighting and biothermal characteristics.The sudden change of solar radiation, temperature, wind and humidity, force the organism to undergo intensive adaptationprocesses. While the change in lighting conditions involves a diurnal rhythm adaptation of the physiological clock(regulated by the hormone melatonin), the change of biothermal factors (represented by UTCI) produce additional stresson the strongly loaded human organism. The field experiment was carried out in Poland and Norway so the impact ofthe selected radiation stimuli on melatonin production could be carried out in conditions of natural constant lighting.The paper presents the results of the preliminary analysis of our research conducted from 22 May to 12 June 2011. Thedistribution of daily outdoor photosynthetically active radiation (PAR) intensity, which is a spectral distribution of solarvisible radiation in selected times of the day were analyzed. Lighting conditions surrounding each subject (doses ofreached energy of visible solar radiation and illumination intensity) were examined as well. Additional adaptation stresscaused by different biothermal conditions (expressed by UTCI index) was also taken into consideration. Diurnal melatoninconcentrations were determined in saliva samples.

Keywords: UTCI, adaptation, diurnal rhythm, lighting conditions, melatonin (MEL), polar day

Joanna Wieczorek, University of Warsaw College of Interfaculty Individual Studies in Mathematics and Natural Sciences Żwirki i Wigury 93, 02-089 Warsaw: Poland
Krzysztof Błażejczyk [k.blaz@twarda.pan.pl], Institute of Geography and Spatial Organization Polish Academy of Sciences Twarda 51/55, 00-818 Warsaw: Poland