Abstract
Drowsiness during driving is a severe problem that must be addressed to improve road safety. Numerous counter-measures have been proposed to resolve this issue like adaptive environmental settings (temperature, sound, and light). The objective of this study was to accurately predict the effects of exposure to different colors of light on human drowsiness by using functional near-infrared spectroscopy and other physical measurements (heart rate and eye closure). We targeted two regions of the brain (visual and pre-frontal cortices). Twenty-three healthy subjects were investigated to evaluate all variables related to the awakening state, and twenty-one healthy subjects were also examined in the drowsy state evaluation. Eventually, the ten most suitable subjects were exposed to red, green, and blue lights under drowsy conditions, according to the experimental paradigm. Dim light was maintained in the experimental premises before and after colored light exposure to limit the results to those produced only in response to the desired stimuli. Eye closure, heart rate, and changes in oxy and deoxy hemoglobin concentrations were measured to characterize the condition (awake/drowsy) of the subject. A support vector machine classifier was used to identify the classification accuracy of awake and drowsy states. In conclusion, exposure to blue light triggered the activation of oxy hemoglobin in targeted brain regions; however, deoxy hemoglobin was not significantly affected by exposure to any of the colored lights. Noticeably, our study revealed that blue light exposure is more effective at reducing drowsiness than exposure to red and green lights.
Highlights
Different colors of light have been incorporated in relevant medical treatments to improve the emotional [1], physical [2], or behavioral condition of patients [3]
IDENTIFICATION OF DROWSY AND AWAKE STATES The trends for twenty-three awake and twenty-one sleep-deprived subjects are presented in Figures 4-6, which show average HbO and HbR concentrations, topographic maps, eye closure and heart rate, respectively
The awake state requires higher oxygen consumption than the drowsy state, resulting in increased cerebral blood flow. This increase in cerebral blood flow/oxygenation, as shown by an increase in HbO concentrations, which indicates that the subject is in the awake state
Summary
Different colors of light have been incorporated in relevant medical treatments to improve the emotional [1], physical [2], or behavioral condition of patients [3]. Blue light is used to treat neonatal hyperbilirubinemia [4], an effect due to abnormal liver function of infants, UV and red lights are used in dermatology [5], and bright light is to temporarily cure mental disorders [6]. The associate editor coordinating the review of this manuscript and approving it for publication was G. Associated generally with coldness [7]. On the other hand, penetrates tissue comparatively deeply and is equated with warmth [8], [9]. Few studies have described the effects of different colors of light on tissue oxygenation [10] and hemodynamics
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