Considerations on the effects of automotive lighting to enhance alert and avoid sleepiness in night time drivers via melatonin inhibition

Abstract

The effects of light on circadian rhythms have been known for a long time. It is well known that shift workers, transoceanic travellers and other people being exposed to light during their sleep hours have remarkable disorders in their biological clocks that can last just some days with few important effects or become really serious with higher incidence of serious diseases. One of the reasons for circadian clock to be altered is the melatonin inhibition, due to the exposure to intense and/or bluer lights during sleep hours. The inhibition of the secretion of this neurohormone has been proven to be an effective measure to enhance alert and avoid sleepiness. However, although this sleepiness avoidance is widely used in indoor illumination to achieve better productivities or higher concentration in mental tasks, nothing has been done in order to ensure that night time drivers will keep awake during long journeys via melatonin inhibition. In this sense, the lighting of the own vehicle could be the most reasonable candidate to avoid sleepiness on this collective with the consequent impact on safety. This work uses the theoretical models of dependence between light intensity and wavelength and melatonin inhibition to analyze the potential influence of car headlamps on sleepiness in people driving during long periods at night-time. The results of this research show that cars equipped with headlamps using xenon and halogen light sources, which are the most common with a still wide advantage on LEDs cause no melatonin inhibition on people driving during long periods at night and thus, the current automotive lighting technology cannot avoid distraction and sleepiness in drivers with this strategy. However, a new lighting pattern that theoretically would cause melatonin inhibition and hence, an enhanced road safety, is proposed. We conclude that the incorporation of headlighting systems providing this pattern would be extremely positive for road safety and one important step for the automotive industry