Variations in diurnal and nocturnal waking state in air traffic controllers.

Physiological variables of 22 air traffic controllers (ATCs), mean age 32, were continuously telemetrically recorded from 08:00 to 17:30 and on the following day from 19:00 to either 00:00 or 0.3:00. EEG (alpha and theta indices, slow delta waves), EOG (palpebral blinks), EMG (from the neck muscles) and EKG (HR) were recorded. Comparison between day and night shows an increase at night of HR and slow waves, particularly after midnight. These results were compared with similar ones obtained from two other populations of the same age having very different professional activities (university personnel and factory workers). The EEG indices and HR are higher in ATCs. The work load imposed by the need in air traffic control to maintain a high level of vigilance, especially difficult after midnight, is in great part responsible for the high values of physiological parameters observed in this study.