Chronotype and Sleep duration in Antarctica: the role of light exposure and social cues in circadian rhythms synchronization

TORTELLO CAMILA; FOLGUEIRA AGUSTÍN; CUIULI JUAN MANUEL; BARBARITO MARTA; DIEGO GOLOMBEK; VIGO DANIEL; PLANO SANTIAGO

Colonia

Simposio; XV Latin American Symposium on Chronobiology; 2019

Light exposure, social schedules and endogenous oscillations entrain circadian rhythms to a 24-h day. Indi- vidual preferences in the timing of sleep and wake, known as chronotypes, are phenotypic expressions of the entrainment phase. Sleep timing is modulated by both the internal clock and environmental cues. Antarc- tica is characterized by up to four month of complete darkness during winter (polar night), configuring an ideal setting to explore the relationship between endogenous and exogenous factors that can affect circadian rhythms. The aim of this research was to analyze the impact of one year of Antarctic isolation on sleep duration and chronotype. During four winter campaigns a total of 64 participants completed the Munich Chronotype Questionnaire (MCTQ) every other month along one year (March-May-July-Sep-Nov). We ana- lyzed mid-sleep during workdays and free days, chronotypes distributions during each month and variations in sleep duration throughout the year. The main result showed significantly later chronotypes (free days mid- sleep) during polar night compared to the others measurement points (p Sep, p < 0.01; July > Nov p < 0.001). No differences were found for mid-sleep during workdays. Our data describe the role of light exposure and social cues in circadian rhythms entrainment within a context of isolation and extreme environment.