Apple's new Night Shift light, as profiled in the San Francisco Chronicle below, does offer a concrete improvement to newer iPhones and iPads: it shifts the color of light coming off the screen, so viewers get exposed to less of the sleep-disrupting blue wavelengths. Very much like the f.lux app does for iOS devices, laptops and some Android phones.
There's solid research that blue light delays sleep by delaying the production of melatonin in the brain, an essential hormone for sleep.
While the new light choice has its benefits, some scientists say it won't help as much as actually turning off your phone two hours before bed. In other words, all of us with ongoing sleep problems won't likely solve them by doing our evening routine of emails, Facebook, online video and binge-watching in sunset colors instead of blue light.