Facebook's creator turned his engineering talents in a new direction -- helping his wife, Priscilla Chan, get .
The box sits on her nightstand and emits a soft glow between 6 and 7 a.m. -- the time their daughters, Maxima and August, usually wake up. The light is faint enough that it won't wake Chan, but visible enough to alert her to the time if she's awake, so she'll know one of them should go and check on the kids.
"So far this has worked better than I expected and she can now sleep through the night," he wrote.
"As an engineer, building a device to help my partner sleep better is one of the best ways I can think of to express my love and gratitude."
Zuckerberg also suggested that some entrepreneur might want to build more sleep boxes so more people can have an alternative to checking the time. But, if you can't wait for the sleep box to go on sale,.
If you want more insights from the social network czar, he recently.
First published at 3:19 a.m. PT.
Updated at 3:44 a.m. PT: Adds more detail.