The light emitted by portable electronic devices (PEDs), particularly when used at night, has drawn a great deal of interest recently. The main concern is over the short-wavelength “blue” light emitted by smartphones, tablets, and even televisions. Exposure to what some call “light at night” (or LAN) can acutely suppress melatonin, a hormone produced at night and in darkness, which tells the body it is nighttime.
In an effort to address this problem, Apple released the Night Shift application for its line of smartphones and tablets. The Night Shift mode permits users to change the screen’s color to “more warm” (i.e., less blue light) or “less warm” (i.e., more blue light), without necessarily changing its brightness. There are apps for the Android operating system that work in a similar way. In theory, reducing the blue light should help the problem with suppression of melatonin. But, does it work? Researchers from the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute looked into the issue.
In the study, LRC researchers Rohan Nagare, Barbara Plitnick, and Mariana G. Figueiro recruited 12 young adults to view iPads between 11:00 p.m. and 1:00 a.m. on four separate nights under four experimental conditions, including a group that used the iPads’ Night Shift feature.
What they found was that melatonin was decreased under all of the conditions. Subjects who used the iPad on regular settings (without Night Shift) had their melatonin levels reduced by 23%. Those who used Night Shift with their screen brightness at a standard level had their melatonin reduced by 19%. A group that used Night Shift and reduced brightness, however, saw melatonin reduced by only 12%.
So, what’s the takeaway? Truly, even reducing melatonin levels by 12% could be enough to disrupt your body’s ability to easily fall asleep. But, if you must use your screens at night, you should not only use a feature like Night Shift, but also turn down the brightness of your device.