EFFECTS OF NIGHTTIME NAP AND DAYTIME SLEEP ON HEART RATE AND DROWSINESS IN LONG-DISTANCE HIGHWAY BUS DRIVERS

The aim of this study was to examine the effects of a nighttime nap and daytime sleep on the heart rates of professional long-distance bus drivers and also a subjective rating of drowsiness through the use of a questionnaire survey on 58 drivers and a heart rate study on 9 drivers during both work and sleep. Of 2 bus drivers, one continued to drive for approximately 2-3 hours while another was alternately able to take a nap during nighttime in the bus cabin for a maximum of around 2 hours during their rest time. In a questionnaire survey, around 80% of 58 drivers reported that they could sleep well for at least one-half of the duration of the nap time reported. The nighttime nap showed a beneficial effect on their sleep debt which results from both night driving as well as from insufficient daytime sleep in local lodgings after duty. Concerning both the nighttime nap and daytime sleep, according to the heart rate measurements of 9 drivers during their duty time, it was found that the average heart rate had higher levels during daytime sleep than during a nighttime nap, presumably due to circadian rhythm. It was disclosed that the duration of a nap in the cabin was very short but the recovery from drowsiness could be effective.