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    • During summers and winters in Antarctica the most extreme an

    2018-10-26

    During summers and winters in Antarctica, the most extreme and isolated continent on earth, the human circadian clock cannot rely on changes of photoperiod and temperature to entrain the clock day after day, and circadian rhythms might tend to free run [17]. Sleep disorders reported in Antarctic crewmembers are probably also related to this dysregulation of the external time cues [18–23]. However, it has been hard to establish to what extent these disorders respond to the external environment rather than to the strictness of social cues and the conditions of isolation inherent to living in an Antarctic nmda receptor antagonist station [24,25].
    Method
    Results
    Discussion This study presents the first characterization of chronobiological parameters from a sample of Uruguayan people. We focused on a very homogeneous population: healthy young adults, attending the same semester at the same University, very restricted in age, within normal BMI, and without signs of depression or other pathologies. We corrected individual MSF for sleep debt, and used MSFsc as the best chronotype proxy, following Roenneberg et al. [11]. Age and gender differences in MSFsc have been previously reported in epidemiological studies in Europe [11,12,27]. We found no statistically significant difference in MSFsc between males and females, probably due to the small size of our sample. Similarly, we were unable to discriminate an effect of age due to the small age window (21–26 y/o). We found no correlation between the MCTQ and SL for any of the sleep parameters analyzed for the pre-Antarctic phase in this study, which was unexpected given the high education level and motivation of the participants to be engaged in the First Uruguayan Summer School on Introduction to Antarctic Research. Discrepancy among instruments has been previously reported [14,28] and was always interpreted as due to inadequate completion of forms, particularly of SL. However, the participants in this study were highly-committed university students and their accuracy and responsibility in filling SL forms was supervised by the researcher team during the study period. Though MCTQ has been validated worldwide, time of-year-dependencies in subjective assessment of sleep wake times have been identified recently [29]. We can thus interpret that pre-Antarctica SL data might have been biased by the fact that students have more relaxed sleep habits during the summertime. In the future, we plan to expand this study to a larger population of students, and to repeat this characterization during the school year.
    Acknowledgments
    Introduction Increase in life expectancy in the recent decades has resulted in the increase in the population of the middle-aged and the elderly men. As they get older, men experience some changes in their physical and mental status due to decrease in androgen; changes like sleep disorders and sexual dysfunction [1,2]. Sleep, constituting one third of the people׳s whole lifetime, has a significant role in the rate of testosterone secretion, studies show that the maximum testosterone secretion rate occurs during sleep mainly rapid eye movement (REM). So, having adequate and high quality sleep is important for having satisfiable erection [3]. Sleep disorder is one of the problems that appears or intensifies with age. As people get older, the advantageous and desirable sleep decreases in them and this matter is associated with decrease in the rate of testosterone and its complications like a decrease in sexual function. The rate of testosterone in half of the healthy men aged 50–70 years is less than that in those aged 20–40 years [2]. Some people get involved with the middle age crisis as a result of the changes due to the decrease of androgen, the symptoms of which usually appear in middle age period and afterward. This crisis appears with sudden and obvious changes like severe depression, increase in taking some drugs, change in lifestyle, changes in working and matrimony relations, and some disorders related to sexual function [4].