Body temperature and time perception in morning and evening types

Previous studies have suggested that time perception fluctuates throughout the day in relation to daily fluctuations of body temperature, and that there is a negative relationship between body temperature and time perception. The aim of this study was to examine, using behavioral and physiological methods, whether evening and morning types differ in their time perception at different times of day using different stimulus durations and whether there is a negative relationship between time perception, body temperature and social jet lag. This study was conducted with 33 participants (17 morning types and 16 evening types) who performed a time production task in four experimental sessions, set on two consecutive days at two times of the day (08.30-10.00 h, 15.30-17.00 h) with four stimulus durations (1, 5, 10 and 15 s). The Morningness-Eveningness Questionnaire (MEQ) and the Munich Chronotype Questionnaire-Turkish version (MCTQ-TR) were used to determine chronotype and social jet lag respectively. The results showed that the produced time was shorter in the evening session than in the morning session. Four stimulus durations were underestimated, and the underestimation increased with stimulus duration. There was also a significant increase in body temperature from morning to evening, but there was no relationship between time perception and body temperature. These results did not support the hypothesis that there is a relationship between time perception and body temperature.