Priscilla Chan found her sleep was impacted by checking the time, so husband Mark Zuckerberg found a way for her to avoid doing so.

Facebook's creator turned his engineering talents in a new direction -- helping his wife, Priscilla Chan, get enough sleep.

Knowing Chan gets stressed when she's aware of the time, Mark Zuckerberg built a wooden "sleep box" to gently let her know it's time to get up, he revealed in a Saturday Instagram post.

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.

Being a mom is hard, and since we've had kids Priscilla has had a hard time sleeping through the night. She'll wake up and check the time on her phone to see if the kids might wake up soon, but then knowing the time stresses her out and she can't fall back asleep. So I worked on building her what I call the "sleep box". It sits on her nightstand, and between the hours of 6-7am it emits a very faint light -- visible enough that if she sees it she'll know it's an okay time for one of us to get the kids, but faint enough that the light won't wake her up if she's still sleeping. And since it doesn't show the time, 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. So far this has worked better than I expected and she can now sleep through the night. 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. A bunch of my friends have told me they'd want something like this, so I'm putting this out there in case another entrepreneur wants to run with this and build sleep boxes for more people!

A post shared by Mark Zuckerberg (@zuck) on Apr 27, 2019 at 9:45am PDT

"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. If you want more insights from the social network czar, he recently started a podcast.

First published at 3:19 a.m. PT.Updated at 3:44 a.m. PT: Adds more detail.