Mark Zuckerberg and his wife Priscilla Chan are experiencing the joys of parenting – including sleep deprivation.

“Being a mom is hard, and since we’ve had kids Priscilla has had a hard time sleeping through the night,” the Facebook founder and CEO wrote  in an Instagram post. The couple have two young girls.

“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.”

To help Chan get more shut eye, Zuckerberg used his engineering knowledge to devise a “sleep box.”

No, she doesn’t sleep inside the box. Placed on Chan’s nightstand, the device emits a “very faint light” between the hours of 6 to 7 a.m. to let her know if it’s time to get up. If it’s not lit, then Chan will know it’s OK to fall back asleep. This way, she won’t have to check the time, which can be a stressor.

“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 wrote.

Dr. Deirdre Conroy, clinical director of the University of Michigan’s behavioral sleep medicine program, said sleep problems among new parents are common.

“I think this idea’s great because so often people with insomnia check their phones throughout the night,” Conroy said. “When you check the time, that triggers this whole stream of worries … and it creates this sense of anxiety.”

She often recommends that patients with sleeping troubles avoid checking the clock during the night.

“Removing that cue for anxiety about how much time she has left to sleep could be helping her sleep through the night,” Conroy added. “There’s so much wrapped up in the symbolism of a clock or a phone that this (sleep box) takes out of it.”

Zuckerberg’s simple creation could help others with sleep issues as well. About 30% of the population has some difficulty sleeping, Conroy said.

The Facebook CEO said he decided to post about his gadget in case another entrepreneur wants to build on his idea and produce sleep boxes to serve more people.