Researchers Remove Uncertainty In Question Of Roadway Lighting Impacts On Human Health

New research from the Virginia Tech Transportation Institute sheds light on the uncertainty of lighting.

A groundbreaking study by the Virginia Tech Transportation Institute (VTTI) found that blue light from LED street lighting did not significantly affect road users' salivary melatonin levels.

Ron Gibbons and Rajaram Bhagavatula, in collaboration with Thomas Jefferson University neuroendocrine researchers George Brainard and John Hannifin, were the first to conduct such a study in a real-world road environment in a DOE-sponsored study. Using the extensive facilities at Smart Roads Virginia, they were able to conduct research with three groups of participants on existing road features and lighting scenarios, which allowed them to publish their research in Clocks & Sleep magazine.

"This is the first study of its kind in a natural environment," said Gibbons, project leader of VTTI's Infrastructure-Based Security Systems group. "This allows us to eliminate the point of uncertainty when testing lighting."

LED bulbs help light the way, save more energy and last longer than traditional yellow-orange High Pressure Sodium (HPS) bulbs, but the American Medical Association is concerned about the negative effects of blue light on humans. In particular, the association has been linked to visual impairment due to the harmful effects of distracting light and light on the environment and human circadian rhythms.

Most of the available research on this topic is based on controlled laboratory experiments. For the study, the team tested the effects of street lighting on melatonin in motorists, pedestrians and people sleeping on the side of the road. This experiment was carried out in natural conditions to be as close as possible to natural phenomena.

Virginia Smart Roads is a complex network of four test beds that recreate everyday driving conditions seen across the country. Using this to further their research, the team developed a test system that replicated everyday scenarios. This includes the use of the Virginia Smart Roads highway segment due to its extensive lighting system that can replicate more than 95% of the lighting in the national highway system, as well as its similarity to real roads.

The team created three test scenarios: Pedestrian participants were asked to sit on the side of the road. Participants in vehicles were asked to drive on a portion of the Virginia Smart Road while the road was illuminated. A final group of participants, located in a simulated roadside dormitory, was asked to sleep in a bed near a window to collect data on light intrusion. Saliva samples were collected periodically and then tested against controls to see if melatonin levels increased after light exposure.

Gibbons and Bhagavatula found that LED lighting had no effect on participants' salivary melatonin levels compared to no street lighting and HPS lighting. Safety, energy, health, light pollution, environmental impact and user preferences are all concerns when it comes to LED lighting. Thanks to their findings, they can help solve a serious problem in terms of its possible impact on human health.

While this project specifically focused on the effects of LED lighting on participants' salivary melatonin levels, the team continues to explore how the lighting saves lives, time, money and the environment.

More information: Ronald B. Gibbons et al., Effects of Solid-State Street Lighting on Melatonin in Humans, Hours, and Sleep (2022). DOI: 10.3390/sleephour4040049

Excerpt : Researcher Uncertainty on Roadway Impacts on Human Health (April 7, 2023), accessed April 8, 2023 at https://medicalxpress.com/news/2023-04-uncertainty-roadway-impacts-human-health.html :

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