Apple this week unveiled a new feature that promises to help millions of users get a better night’s sleep. The feature is called Night Shift, and it works by reducing the amount of blue light pouring off your screen when the sun goes down.

It’s an ingenious idea since over-exposure to blue light is what leaves so many of us addled and restless in the first place — those of us, that is, who get themselves all wired up by staring at their phone screen (and its blue light) in bed.

In theory, Apple’s AAPL idea sounds like an obvious and simple solution: Less blue light, less trouble getting to sleep. Alas, there’s a catch, and it comes in the form of unintended consequences.

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According to a sleep doctor cited by Business Insider, Apple’s new Night Shift feature could actually lead to a worse sleep, since blue light isn’t the only thing that interferes with our sleep. Another big trouble factor is excess stimulation—like all those emails, articles, and stimulating Facebook videos you find on your phone.

In other words, there’s a risk many consumers will treat the Night Shift feature as an excuse to look at their phone in bed more than ever. And so their restless nights will continue.

The real sleep solution, of course, is to ditch the gadgets altogether and “power down” in the half hour before bed. I actually began doing this a few months ago, by putting down my phone and picking up a paper book—and I swear it works! It’s more relaxing, and I fall asleep sooner than I did when I stayed up clutching my phone.

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Of course, not all devices are alike. Dedicated e-readers, including many types of Kindle AMZN , do not throw off blue light, so they won’t mess with your sleep in the way an iPad will.

But that doesn’t mean you shouldn’t use the Night Shift feature. As the sleep doctor noted, less blue light is better—just remember to follow the other rules for sound sleeping.