Researchers at Photoprotective Technologies (PPT) introduced a rating system for determining the ability of blue light-filtering computer glasses to preserve the nighttime production of melatonin. The patent-pending “Melatonin Production Factor”—or MPF—can rate any computer eyewear to let you know how much longer you can use your electronic display before you get a 22% loss of melatonin (what PPT says occurs after 2 hours of blue light exposure from an iPad without any protective eyewear).

A lens with an MPF value of 3, for example, means that you can use the iPad 3 times longer with that lens—or 6 hours—to get the same 22% loss of melatonin that you would get without that lens. “It’s possible to get really high MPF values by blocking all of the blue light,” says Jim Gallas, PhD, co-inventor of the rating system and PPT CEO in a release, ”but then you lose your perception of color. We knew that lenses with melanin were able to filter significant amounts of blue light and still preserve the colors.”

To determine the MPF value of any lens, a transmission spectrum is recorded for the lens and serves as the input to an Excel-based spreadsheet containing the MPF algorithm created by PPT. Lenses infused with melanin have high MPF values. Melanin is the organic pigment in the hair and eyes of every human. Gallas and his staff then proceeded to modify their melanin technology to arrive at MPF values as high as 6—making it possible for computer users to extend their night time marathon habits up to 12 hours. “The technology is very broad with other applications—including light filters for LED and fluorescent lighting and film covers for iPhones,” Gallas says.