Use of temperature variations to combat drivers' drowsiness.

The purpose of the present study was to evaluate the efficiency of temperature variations as a measure against drivers' drowsiness. A system for regulation of the air temperature in the cab was installed in two trucks. Irregular temperature reductions of about 8 degrees C were introduced. The periods between the temperature reductions varied among 5, 6, 7, and 8 min. The periods for the temperature reductions varied between 2, 4, 6, and 8 min. The system was tested with 6 drivers on 54 trips. The system was applied for periods varying between 30 to 300 min. Changes in wakefulness were analysed using subjective ratings by the lorry drivers. The application of the system significantly improved subjectively rated wakefulness. The wakefulness was rated with a questionnaire completed after 10 min. use of a cooling system and at the end of its use. Analysis showed individual differences in the usefulness of the system: 3 of the 6 truck drivers reported positive reactions to the use of the temperature cooling system.