Mark Zuckerberg built a glowing wooden box to help his wife sleep. Here are 3 similar gadgets you can actually buy.

• Facebook CEO Mark Zuckerberg built a glowing wooden box to help his wife sleep, he recently revealed in an Instagram post.
• The box emits light to wake her up without requiring her to look at the time.
• While it's not possible to buy that device, there are a few products available that use light to wake you up, help you fall asleep, and relieve stress.
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Even the world's wealthiest people can have trouble sleeping, as Facebook CEO Mark Zuckerberg reminded us over the weekend when he showcased the glowing wooden box he built to help his wife sleep.

In an Instagram post, Zuckerberg noted that his wife, Priscilla Chan, has a difficult time sleeping through the night. As many people likely do, Chan often checks the time when she wakes up to see if the kids will be awake soon. But knowing the time stresses her out and makes it hard for her to fall back asleep, the Facebook CEO wrote.

So he constructed a wooden "sleep box" that emits a faint light between 6 a.m. and 7 a.m. The light is noticeable enough to let her know that it might be time for the kids to wake up, but it won't wake her up if she's already asleep, he says.

Zuckerberg's sleep device isn't for sale, but there are a whole category of sunrise alarm clocks that use light to provide a more natural wake-up experience.

If looking at the clock as soon as you wake up stresses you out too, here are some similar devices you can purchase that don't prominently display the time.