Blue-Enriched Light Enhances Alertness but Impairs Accurate Performance in Evening Chronotypes Driving in the Morning

Abstract

Attention maintenance is highly demanding and typically leads to vigilance decrement along time on task. Therefore, performance in tasks involving vigilance maintenance for long periods, such as driving, tends to deteriorate over time. Cognitive performance has been demonstrated to fluctuate over 24 h of the day (known as circadian oscillations), thus showing peaks and troughs depending on the time of day (leading to optimal and suboptimal times of day, respectively). Consequently, vigilance decrements are more pronounced along time on task when it is performed at suboptimal times of day. According to research, light exposure (especially blue-enriched white) enhances alertness. Thus, it has been proposed to prevent the vigilance decrement under such adverse circumstances. We aimed to explore the effects of blue-enriched white light (vs. dim light) on the performance of a simulated driving task at a suboptimal time of day. A group of evening-types was tested at 8 am, as this chronotype had previously shown their largest vigilance decrement at that time. In the dim light condition, vigilance decrements were expected on both subjective (as increments in the Karolinska Sleepiness Scale scores) and behavioral measures [as slower reaction times (RTs) in the auditory Psychomotor Vigilance Task, slower RTs to unexpected events during driving, and deteriorated driving accuracy along time on task]. Physiological activation was expected to decrease (as indexed by an increase of the distal-proximal temperature gradient, DPG). Under blue-enriched white light, all these trends should be attenuated. Results from the control dim light condition replicated the vigilance decrement in all measures. Most important, the blue-enriched white light attenuated this decrement, leading to both lower DPG and faster RTs. However, it impaired accuracy of driving performance, and did not have any effect on subjective sleepiness. We conclude that exposure to blue-enriched light provides an effective countermeasure to enhance vigilance performance at suboptimal times of day, according to measures such as RTs. However, it should be considered that alerting effects of light could impair accuracy in precision tasks as keeping a proper car position. The current findings provide ergonomic implications for safety and fatigue related management systems.

The Role of Exercise-Induced Arousal and Exposure to Blue-Enriched Lighting on Vigilance

“…Lighting, however, did not influence skin temperature in this experiment, in contrast with many previous evidence (Badia et al, 1991; Cajochen et al, 2005; Lockley et al, 2006; Correa et al, 2016; Rodríguez-Morilla et al, 2017, 2018). The main difference between the abovementioned studies and the current one is that participants were at rest in the former while they were engaged in physical activity in all of our conditions.…”

“…However, this evidence becomes weaker at the behavioral level, as many studies have not confirmed that lighting effects improve task performance. A systematic review of the literature has revealed that from 17 studies testing the behavioral effects of bright white light as measured by a simple reaction time (RT) task, such as the psychomotor vigilance task (PVT; Dinges and Powell, 1985), only two of them reported significant effects on RT performance (Souman et al, 2017; see also Rodríguez-Morilla et al, 2018). Other studies using more complex tasks, like the n-back, have also failed to report behavioral effects of light (Vandewalle et al, 2007a,b).…”

Human-Centric Lighting: Foundational Considerations and a Five-Step Design Process

“…During daytime hours, improvements in alertness may be minimal for well-rested people ( 88 ). Many studies of alertness and cognition have shown mixed results where some measures have improved but others have not ( 15 , 89 – 92 ).…”

Feasibility and acute alerting effects of a daylight-supplementing in-vehicle lighting system – Results from two randomised controlled field studies during dawn and dusk

“…Research into the effects of light on car drivers is scarce and has, thus far, mainly investigated the effects of low-intensity, narrowband blue light during nighttime driving. [37][38][39][40][41] To our best knowledge, only one study has quantified the potential of artificially increased light exposure to increase alertness while driving trucks under naturalistic, daytime conditions. 42 However, no studies to our knowledge have investigated this non-visual effect in passenger cars during the daytime.…”

“…As a consequence, light impact research in cars during the night has primarily been conducted in driving simulators. 39,40 It can be hypothesised that increasing invehicle light levels during periods of high daylight levels may not evoke arousal effects due to four reasons. First, natural corneal light levels of drivers are high on sunny days (2900 lux; as reported in our unpublished research) and adding light may not have an arousing effect.…”