The present studies examined the feasibility and acute alerting effects of additional in-vehicle lighting within a passenger car. These factors were examined during morning driving (Study 1) and evening driving (Study 2). In a balanced within-subjects design, 37 participants drove a test car two times in the morning or in the evening. The test vehicle was equipped with either a daylight-supplementing interior lighting system or a placebo system, which participants were told would refresh the air. Both studies used identical protocols, and participants participated either in Study 1 (n = 18) or Study 2 (n = 19). In both studies, corneal illuminance levels were recorded while driving. Feasibility of the systems was assessed using subjective ratings. Efficacy outcomes were spindle rates in the alpha bandwidth of electroencephalogram recordings, performance on a psychomotor vigilance task and subjective sleepiness ratings. In both studies, daylight-supplementing significantly increased corneal illuminances while driving and did not cause any negative visual side-effects. Study 1 revealed lower spindle rates while driving under daylight-supplementing lighting, indicating that drivers had higher physiological alertness when exposed to additional light in the morning. This alerting effect of daylight-supplementing lighting, however, was not observed in Study 2. In both studies, performance on the psychomotor vigilance task as well as subjective sleepiness ratings did not significantly differ between the experimental conditions. The present studies provide novel evidence for the feasibility and positive impact of daylight-supplementing in-vehicle lighting systems on the physiological alertness of drivers under naturalistic driving conditions. Further studies are warranted to evaluate carry-over effects of increased alertness on road safety measures.

本研究检查了乘用车内附加车载照明的可行性和急性警报作用。在早晨驾驶（研究1）和晚上驾驶（研究2）期间检查了这些因素。在均衡的受试者内部设计中，有37名参与者在早上或晚上两次驾驶了测试车。测试车辆配备了日光补给的室内照明系统或安慰剂系统，参与者被告知将刷新空气。两项研究均使用相同的方案，参与者参加了研究1（n  = 18）或研究2（n = 19）。在两项研究中，驾驶时均记录了角膜照度水平。系统的可行性是使用主观评分进行评估的。疗效结果为脑电图记录的α带宽中的纺锤体率，对精神运动警觉任务的表现以及主观嗜睡程度。在两项研究中，补充日光在驾驶时都会显着增加角膜照度，并且不会引起任何负面的视觉副作用。研究1显示，在日光辅助照明下驾驶时，纺锤率较低，这表明驾驶员在早晨暴露于其他光线下时具有较高的生理机敏性。然而，在研究2中未观察到这种补充日光的警报效果。在实验条件之间，对精神运动警觉任务的表现以及主观嗜睡等级没有显着差异。本研究为自然采光条件下补充日光的车载照明系统对驾驶员的生理机敏性的可行性和积极影响提供了新的证据。有必要进行进一步的研究，以评估提高警觉性对道路安全措施的影响。