Facebook is under federal investigation, so you'd think Mark Zuckerberg might be feeling stressed. But it's his wife's stress he's been trying to ease, Quartz reports. Priscilla Chan had been waking up in the early morning and reaching for her phone to see whether their two children would be getting up soon, Zuckerberg posted on Instagram. "Knowing the time stresses her out," he wrote, "and she can't fall back asleep." So Zuckerberg built what he calls a "sleep box" for her nightstand. It emits a faint light between 6am and 7am. "If she wakes up in the middle of the night, she knows to just go back to sleep without having to worry about what time it is." Chan, a pediatrician, is sleeping better now, he says.
The alarm was a hit outside their house, too. "I have been through this when my kid was young, all the time I was sleep deprived," one Facebook post read, per USA Today. "You are such an amazing husband." Zuckerberg suggested that someone else might want to build such an alarm and market it, but other posters said similar products already are on the market. One reason Chan is sleeping better might be the fact that the device has no screen, Quartz points out. Research indicates that the brain sees the display on a smartphone as daylight, which suppresses melatonin, the hormone linked to healthy circadian rhythms. Zuckerberg gave no hints about his sleep patterns or stress level, but he did suggest his responsibilities extend beyond giving his wife a cool alarm: He posted that Chan knows when the light appears that "it's an okay time for one of us to get the kids." (It can be years before new parents are past the sleep-deprived stage, a study found.)