Transportation Driving

Study explores LED roadway lighting’s impact on driver alertness, sleep health

Photo: kievith/iStockphoto

Washington — A National Academies of Sciences, Engineering and Medicine study of the effects of LED roadway lighting on driver alertness and sleep health has found that, despite concerns, LED lighting is no worse than another common type of roadway lighting.

Researchers conducted five experimental sessions in which 10 healthy participants between the ages of 18 and 30 with a steady sleep-wake cycle encountered different light types (LED and high-pressure sodium lights) and levels during each session. Participant sleep health was evaluated based on melatonin levels in saliva, while driver alertness was measured objectively via multiple observations and subjectively using the Karolinska Sleepiness Scale.

The researchers found that the participants exhibited no statistical difference in melatonin levels after exposure to the same LED and HSP light levels. In addition, no differences were discovered between LED and HPS road light exposure versus roadways with no lighting. Exposure to higher levels of LED lighting also had no difference in the participants’ melatonin levels.


Driver alertness was adversely affected with more exposure to HPS lighting, as researchers noticed a decrease in detection and color-recognition distances. Such differences weren’t observed under LED lighting, however. Finally, no statistical differences were found between the HPS, LED and no lighting roadway conditions for subjective driver alertness, as measured by the KSS.

The report was published April 2 and can be downloaded for free via the Transportation Research Board website.

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