In-Car Nocturnal Blue Light Exposure Improves Motorway Driving: A Randomized Controlled Trial

<div><p>Prolonged wakefulness greatly decreases nocturnal driving performance. The development of in-car countermeasures is a future challenge to prevent sleep-related accidents. The aim of this study is to determine whether continuous exposure to monochromatic light in the short wavelengths (blue light), placed on the dashboard, improves night-time driving performance. In this randomized, double-blind, placebo-controlled, cross-over study, 48 healthy male participants (aged 20–50 years) drove 400 km (250 miles) on motorway during night-time. They randomly and consecutively received either continuous blue light exposure (GOLite, Philips, 468 nm) during driving or 2*200 mg of caffeine or placebo of caffeine before and during the break. Treatments were separated by at least 1 week. The outcomes were number of inappropriate line crossings (ILC) and mean standard deviation of the lateral position (SDLP). Eight participants (17%) complained about dazzle during blue light exposure and were removed from the analysis. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0046750#s3" target="_blank">Results</a> from the 40 remaining participants (mean age ± SD: 32.9±11.1) showed that countermeasures reduced the number of inappropriate line crossings (ILC) (F(2,91.11) = 6.64; p<0.05). Indeed, ILC were lower with coffee (12.51 [95% CI, 5.86 to 19.66], p = 0.001) and blue light (14.58 [CI, 8.75 to 22.58], p = 0.003) than with placebo (26.42 [CI, 19.90 to 33.71]). Similar results were found for SDLP. Treatments did not modify the quality, quantity and timing of 3 subsequent nocturnal sleep episodes. Despite a lesser tolerance, a non-inferior efficacy of continuous nocturnal blue light exposure compared with caffeine suggests that this in-car countermeasure, used occasionally, could be used to fight nocturnal sleepiness at the wheel in blue light-tolerant drivers, whatever their age. More studies are needed to determine the reproducibility of data and to verify if it can be generalized to women.</p><p>Trial Registration</p><p><a href="http://ClinicalTrials.gov" target="_blank">ClinicalTrials.gov</a><a href="http://clinicaltrials.gov/ct2/show/NCT01070004" target="_blank">NCT01070004</a></p></div

Participant flow: The numbers of participants who were randomly assigned, received intended treatment and were analyzed for the primary outcome.

<p>Participant flow: The numbers of participants who were randomly assigned, received intended treatment and were analyzed for the primary outcome.</p

Driving Performance: Mean cumulative number of inappropriate line crossings in all substance conditions.

<p>* P<0.01.</p

Percentages of drivers without ADHD symptoms and drivers with ADHD symptoms reporting near miss driving accidents.

<p>Percentages of drivers without ADHD symptoms and drivers with ADHD symptoms reporting near miss driving accidents.</p

Design of the protocol representing the sleep-wake period and the duration of each nocturnal driving session (short, intermediate and long durations of driving).

<p>Design of the protocol representing the sleep-wake period and the duration of each nocturnal driving session (short, intermediate and long durations of driving).</p

Demographic characteristics of 34597 drivers without ADHD symptoms versus 1543 drivers with ADHD symptoms.

<p>Demographic characteristics of 34597 drivers without ADHD symptoms versus 1543 drivers with ADHD symptoms.</p

Percentages of drivers without ADHD symptoms and drivers with ADHD symptoms reporting driving accidents.

<p>Percentages of drivers without ADHD symptoms and drivers with ADHD symptoms reporting driving accidents.</p

Cumulative number of inappropriate line crossings (ILC) for the 14 subjects in the last hour of the 3 nocturnal driving sessions (short, intermediate and long durations of driving), as well as the ILC for the reference drive (9–10 pm of the long drive).

<p>Statistical analyses refer to Incidence rate ratios (IRR) with 95% confidence intervals (CI) using the short drive and the 9–10 pm drive as reference (See section <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0003493#s3" target="_blank">results</a>). * P<.05. ** P<.001.</p

Time course of the percentage of missed Go in the Go/Nogo task of the young and the older group under SD and NAP conditions (mean values ± SEM).

<p>SD  =  Sleep deprivation.</p

Regression analysis of measures associated with mean daily CPAP use.

<p>Regression analysis of measures associated with mean daily CPAP use.</p