Lighting Research Center Lighting Research Center

GlareVisual Recovery and Discomfort Following Exposure to Oncoming Headlamps

Glare from oncoming headlamps is frequently cited by drivers as a major traffic hazard. There have been many studies that have looked into the impact that headlight glare has on visibility and sensations of annoyance, but few studies have looked at how headlight glare affects you in the seconds after your eye adjusts to the headlight. LRC researchers have looked at the time it takes to recovery from headlight exposure.

Following exposure to oncoming headlights, photoreceptors in the eye must re-adapt to the lower light levels. Adjusting to the darkness once again takes a longer amount of time than adjusting to bright light. This adjustment period of time has serious consequences on the roadway safety since drivers cannot always see objects on the side of the road during this period.

LRC investigators showed that recovery time was longest when objects were located on the periphery. Similarly, recovery time was longest when the dosage of light was higher. However, discomfort is driven more by peak illuminance than by light dosage. Interestingly, the age of the subjects (mean age of 25 and 55 year old) showed large differences in recovery time but virtually no difference in terms of their discomfort levels.

The results of this study provided field verification of an earlier laboratory study by Van Derlofske in 2005.

Lighting Research Center reports published by NHTSA:


Skinner, N. P. and J. D. Bullough. 2009. Visual recovery and discomfort following exposure to oncoming headlamps (reprint of SAE paper 2009-01-0546). Society of Automotive Engineers International Journal of Passenger Cars - Mechanical Systems 2(1): 745-749.


National Highway Traffic Safety Administration

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