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BOB HIRSHON (host):
Proceeding with caution on yellow lights. I’m Bob Hirshon and this is Science Update.
If you hit your breaks as soon as you see a yellow light, the car behind you could slam into you; sail through the light, and a car could hit you from the side. Heshem Rakhar at Virginia Tech tries to find the best timing for yellow lights to give drivers with slower reaction times long enough to stop, without encouraging daredevils to press their luck. In most cases, he’s found that 4.2 seconds on a 45 mph road is ideal. Rakhar says that one day, in-car systems may provide warnings that adjust to individual drivers and weather conditions.
In other news, researchers in Israel report that lights, TVs, and computer screens are wreaking havoc with the body’s circadian rhythms, causing chronic disorders. Since avoiding artificial light is nearly impossible, scientists are looking at adjusting the light’s wavelengths to minimize the problem. I’m Bob Hirshon, for AAAS, the science society.