Directors: Antonio M. Battro and Kurt W. Fischer
Program officer: María Lourdes Majdalani
Circadian rhythms in attention
Circadian rhythms in performance may be due to variations in basic cognitive processes, such as attention. Attention involves different components: tonic alertness, phasic alertness, selective attention and sustained attention. The aim of this study was to identify possible circadian variations in the components of attention. Fifteen female undergraduate students (mean age 18 yr, SD = 1.31, range 16 – 21 yr) participated voluntarily in this study; they attended classes from 07:00 to 13:30 h, from Monday to Friday. Each subject was recorded in a constant routine protocol for 30 h. During this recording session, rectal temperature was measured at one-minute intervals; sleepiness, tiredness and a continuous performance task were assessed each hour. Performance measures showed a decline through the 30 h session. Tonic alertness, phasic alertness and selective attention showed circadian variations; lower levels occurred from 04:00 to 07:00 h. Sustained attention did not show circadian variations. Circadian variations in these components of attention are critical for the performance of many tasks, such as memory, reading, and arithmetic calculation. These may interfere with academic achievement, productivity at work, and may produce a higher risk of accidents.