External auditory canal temperature and reaction time relationship during long performances.

In order to study the relationship between body temperature and reaction time (RT), and check the hypothesis proposed by Kleitman (Sleep and Wakefulness, University Press, Chicago, 1963) about a 'Basic Rest-Activity Cycle' (BRAC), RT tasks were delivered to 24 subjects at 10-min intervals for 320 min, while simultaneously registering bilateral ear canal temperatures. Time series analyses in frequency and time domains were applied to the data. Our results did not show a 90-100 min ultradian rhythmicity in the performance of RT tasks, but 6 of the 24 subjects presented significant periods within limits of BRAC in temperature.